diff --git a/openslides/__main__.py b/openslides/__main__.py
index 6af8aa3ab..951fb1123 100644
--- a/openslides/__main__.py
+++ b/openslides/__main__.py
@@ -3,6 +3,7 @@
 import os
 import subprocess
 import sys
+from typing import Dict  # noqa
 
 import django
 from django.core.management import call_command, execute_from_command_line
@@ -88,7 +89,7 @@ def get_parser():
         dest='subcommand',
         title='Available subcommands',
         description="Type '%s <subcommand> --help' for help on a "
-                    "specific subcommand." % parser.prog,
+                    "specific subcommand." % parser.prog,  # type: ignore
         help='You can choose only one subcommand at once.',
         metavar='')
 
@@ -155,8 +156,8 @@ def get_parser():
         ('runserver', 'Starts the Tornado webserver.'),
     )
     for django_subcommand, help_text in django_subcommands:
-        subparsers._choices_actions.append(
-            subparsers._ChoicesPseudoAction(
+        subparsers._choices_actions.append(  # type: ignore
+            subparsers._ChoicesPseudoAction(  # type: ignore
                 django_subcommand,
                 (),
                 help_text))
@@ -248,7 +249,7 @@ def createsettings(args):
     """
     settings_path = args.settings_path
     local_installation = is_local_installation()
-    context = {}
+    context = {}  # type: Dict[str, str]
 
     if local_installation:
         if settings_path is None:
diff --git a/openslides/agenda/access_permissions.py b/openslides/agenda/access_permissions.py
index 2bd281c80..9dbcf0491 100644
--- a/openslides/agenda/access_permissions.py
+++ b/openslides/agenda/access_permissions.py
@@ -1,4 +1,9 @@
-from ..utils.access_permissions import BaseAccessPermissions
+from typing import Iterable  # noqa
+
+from ..utils.access_permissions import (  # noqa
+    BaseAccessPermissions,
+    RestrictedData,
+)
 from ..utils.auth import has_perm
 from ..utils.collection import Collection
 
@@ -55,17 +60,17 @@ class ItemAccessPermissions(BaseAccessPermissions):
 
                 # In hidden case managers and non managers see only some fields
                 # so that list of speakers is provided regardless.
-                blocked_keys_hidden_case = full_data[0].keys() - (
+                blocked_keys_hidden_case = set(full_data[0].keys()) - set((
                     'id',
                     'title',
                     'speakers',
                     'speaker_list_closed',
-                    'content_object')
+                    'content_object'))
 
                 # In non hidden case managers see everything and non managers see
                 # everything but comments.
                 if has_perm(user, 'agenda.can_manage'):
-                    blocked_keys_non_hidden_case = []
+                    blocked_keys_non_hidden_case = []  # type: Iterable[str]
                 else:
                     blocked_keys_non_hidden_case = ('comment',)
 
@@ -81,7 +86,7 @@ class ItemAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
@@ -111,7 +116,7 @@ class ItemAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            projector_data = data
+            projector_data = data  # type: RestrictedData
         elif data:
             projector_data = data[0]
         else:
diff --git a/openslides/agenda/models.py b/openslides/agenda/models.py
index 090668721..733e349f6 100644
--- a/openslides/agenda/models.py
+++ b/openslides/agenda/models.py
@@ -1,4 +1,5 @@
 from collections import defaultdict
+from typing import Dict, List, Set  # noqa
 
 from django.conf import settings
 from django.contrib.auth.models import AnonymousUser
@@ -79,7 +80,7 @@ class ItemManager(models.Manager):
         HIDDEN_ITEM and all of their children.
         """
         queryset = self.order_by('weight')
-        item_children = defaultdict(list)
+        item_children = defaultdict(list)  # type: Dict[int, List[Item]]
         root_items = []
         for item in queryset:
             if only_agenda_items and item.type == item.HIDDEN_ITEM:
@@ -135,7 +136,7 @@ class ItemManager(models.Manager):
                 yield (element['id'], parent, weight)
                 yield from walk_items(element.get('children', []), element['id'])
 
-        touched_items = set()
+        touched_items = set()  # type: Set[int]
         db_items = dict((item.pk, item) for item in Item.objects.all())
         for item_id, parent_id, weight in walk_items(tree):
             # Check that the item is only once in the tree to prevent invalid trees
@@ -293,7 +294,7 @@ class Item(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='agenda/list-of-speakers',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     @property
     def title(self):
diff --git a/openslides/agenda/signals.py b/openslides/agenda/signals.py
index 68c572dd4..7fff95ea7 100644
--- a/openslides/agenda/signals.py
+++ b/openslides/agenda/signals.py
@@ -1,3 +1,5 @@
+from typing import Set  # noqa
+
 from django.apps import apps
 from django.contrib.contenttypes.models import ContentType
 
@@ -62,7 +64,7 @@ def required_users(sender, request_user, **kwargs):
     if request_user can see the agenda. This function may return an empty
     set.
     """
-    speakers = set()
+    speakers = set()  # type: Set[int]
     if has_perm(request_user, 'agenda.can_see'):
         for item_collection_element in Collection(Item.get_collection_string()).element_generator():
             full_data = item_collection_element.get_full_data()
diff --git a/openslides/assignments/access_permissions.py b/openslides/assignments/access_permissions.py
index 56f5f2afc..8cd760ef5 100644
--- a/openslides/assignments/access_permissions.py
+++ b/openslides/assignments/access_permissions.py
@@ -1,4 +1,7 @@
-from ..utils.access_permissions import BaseAccessPermissions
+from ..utils.access_permissions import (  # noqa
+    BaseAccessPermissions,
+    RestrictedData,
+)
 from ..utils.auth import has_perm
 from ..utils.collection import Collection
 
@@ -50,7 +53,7 @@ class AssignmentAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
@@ -76,7 +79,7 @@ class AssignmentAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            projector_data = data
+            projector_data = data  # type: RestrictedData
         elif data:
             projector_data = data[0]
         else:
diff --git a/openslides/assignments/apps.py b/openslides/assignments/apps.py
index 487fc9618..6bb4d2e00 100644
--- a/openslides/assignments/apps.py
+++ b/openslides/assignments/apps.py
@@ -1,4 +1,7 @@
+from typing import Dict, List, Union  # noqa
+
 from django.apps import AppConfig
+from mypy_extensions import TypedDict
 
 from ..utils.collection import Collection
 
@@ -46,9 +49,11 @@ class AssignmentsAppConfig(AppConfig):
 
     def get_angular_constants(self):
         assignment = self.get_model('Assignment')
+        InnerItem = TypedDict('InnerItem', {'value': int, 'display_name': str})
+        Item = TypedDict('Item', {'name': str, 'value': List[InnerItem]})  # noqa
         data = {
             'name': 'AssignmentPhases',
-            'value': []}
+            'value': []}  # type: Item
         for phase in assignment.PHASES:
             data['value'].append({
                 'value': phase[0],
diff --git a/openslides/assignments/models.py b/openslides/assignments/models.py
index 8fad3e681..ede9fe5d8 100644
--- a/openslides/assignments/models.py
+++ b/openslides/assignments/models.py
@@ -1,4 +1,5 @@
 from collections import OrderedDict
+from typing import Any, Dict, List, Optional  # noqa
 
 from django.conf import settings
 from django.contrib.contenttypes.fields import GenericRelation
@@ -174,7 +175,7 @@ class Assignment(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='assignments/assignment',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore # TODO fix typing
 
     @property
     def candidates(self):
@@ -300,14 +301,14 @@ class Assignment(RESTModelMixin, models.Model):
         Returns a table represented as a list with all candidates from all
         related polls and their vote results.
         """
-        vote_results_dict = OrderedDict()
+        vote_results_dict = OrderedDict()  # type: Dict[Any, List[AssignmentVote]]
 
         polls = self.polls.all()
         if only_published:
             polls = polls.filter(published=True)
 
         # All PollOption-Objects related to this assignment
-        options = []
+        options = []  # type: List[AssignmentOption]
         for poll in polls:
             options += poll.get_options()
 
@@ -317,7 +318,7 @@ class Assignment(RESTModelMixin, models.Model):
                 continue
             vote_results_dict[candidate] = []
             for poll in polls:
-                votes = {}
+                votes = {}  # type: Any
                 try:
                     # candidate related to this poll
                     poll_option = poll.get_options().get(candidate=candidate)
@@ -429,7 +430,7 @@ class AssignmentPoll(RESTModelMixin, CollectDefaultVotesMixin,  # type: ignore
             name='assignments/assignment',
             id=self.assignment.pk,
             poll=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore  # TODO: fix typing
 
     def get_assignment(self):
         return self.assignment
diff --git a/openslides/assignments/signals.py b/openslides/assignments/signals.py
index c3a88c102..d36589243 100644
--- a/openslides/assignments/signals.py
+++ b/openslides/assignments/signals.py
@@ -1,3 +1,5 @@
+from typing import Any, Set  # noqa
+
 from django.apps import apps
 
 from ..utils.auth import has_perm
@@ -22,7 +24,7 @@ def required_users(sender, request_user, **kwargs):
     options) in any assignment if request_user can see assignments. This
     function may return an empty set.
     """
-    candidates = set()
+    candidates = set()  # type: Set[Any]  # TODO: Replace Any
     if has_perm(request_user, 'assignments.can_see'):
         for assignment_collection_element in Collection(Assignment.get_collection_string()).element_generator():
             full_data = assignment_collection_element.get_full_data()
diff --git a/openslides/core/config.py b/openslides/core/config.py
index 22e671c33..7a7ed689c 100644
--- a/openslides/core/config.py
+++ b/openslides/core/config.py
@@ -1,13 +1,4 @@
-from typing import (
-    Any,
-    Callable,
-    Dict,
-    Iterable,
-    List,
-    Optional,
-    TypeVar,
-    Union,
-)
+from typing import Any, Callable, Dict, Iterable, Optional, TypeVar, Union
 
 from django.core.exceptions import ValidationError as DjangoValidationError
 from django.utils.translation import ugettext as _
@@ -192,9 +183,9 @@ use x = config[...], to set it use config[...] = x.
 
 
 T = TypeVar('T')
-ChoiceType = Optional[List[Dict[str, str]]]
+ChoiceType = Optional[Iterable[Dict[str, str]]]
 ChoiceCallableType = Union[ChoiceType, Callable[[], ChoiceType]]
-ValidatorsType = List[Callable[[T], None]]
+ValidatorsType = Iterable[Callable[[T], None]]
 OnChangeType = Callable[[], None]
 ConfigVariableDict = TypedDict('ConfigVariableDict', {
     'key': str,
diff --git a/openslides/core/management/commands/getgeiss.py b/openslides/core/management/commands/getgeiss.py
index 53ae1724e..cbb9510dc 100644
--- a/openslides/core/management/commands/getgeiss.py
+++ b/openslides/core/management/commands/getgeiss.py
@@ -51,7 +51,7 @@ class Command(BaseCommand):
         response = urlopen(self.get_geiss_url()).read()
         releases = json.loads(response.decode())
         for release in releases:
-            version = distutils.version.StrictVersion(release['tag_name'])
+            version = distutils.version.StrictVersion(release['tag_name'])  # type: ignore
             if version < self.FIRST_NOT_SUPPORTED_VERSION:
                 break
         else:
diff --git a/openslides/core/models.py b/openslides/core/models.py
index 5b165f0fe..ce0c8f021 100644
--- a/openslides/core/models.py
+++ b/openslides/core/models.py
@@ -111,7 +111,7 @@ class Projector(RESTModelMixin, models.Model):
         """
         # Get all elements from all apps.
         elements = {}
-        for element in ProjectorElement.get_all():
+        for element in ProjectorElement.get_all():  # type: ignore
             elements[element.name] = element
 
         # Parse result
@@ -138,7 +138,7 @@ class Projector(RESTModelMixin, models.Model):
         """
         # Get all elements from all apps.
         elements = {}
-        for element in ProjectorElement.get_all():
+        for element in ProjectorElement.get_all():  # type: ignore
             elements[element.name] = element
 
         # Generator
@@ -169,7 +169,7 @@ class Projector(RESTModelMixin, models.Model):
             elements = {}
 
             # Build projector elements.
-            for element in ProjectorElement.get_all():
+            for element in ProjectorElement.get_all():  # type: ignore
                 elements[element.name] = element
 
             # Iterate over all active projector elements.
@@ -341,7 +341,7 @@ class ProjectorMessage(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='core/projector-message',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
 
 class Countdown(RESTModelMixin, models.Model):
@@ -370,7 +370,7 @@ class Countdown(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='core/countdown',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     def control(self, action):
         if action not in ('start', 'stop', 'reset'):
diff --git a/openslides/core/views.py b/openslides/core/views.py
index 666d5bbe2..9a1115978 100644
--- a/openslides/core/views.py
+++ b/openslides/core/views.py
@@ -3,6 +3,7 @@ import uuid
 from collections import OrderedDict
 from operator import attrgetter
 from textwrap import dedent
+from typing import Any, Dict, List  # noqa
 
 from django.apps import apps
 from django.conf import settings
@@ -11,6 +12,7 @@ from django.db.models import F
 from django.http import Http404, HttpResponse
 from django.utils.timezone import now
 from django.utils.translation import ugettext as _
+from mypy_extensions import TypedDict
 
 from .. import __version__ as version
 from ..utils import views as utils_views
@@ -105,7 +107,7 @@ class WebclientJavaScriptView(utils_views.View):
     """
     def get(self, *args, **kwargs):
         angular_modules = []
-        js_files = []
+        js_files = []  # type: List[str]
         realm = kwargs.get('realm')  # Result is 'site' or 'projector'
         for app_config in apps.get_app_configs():
             # Add the angular app if the module has one.
@@ -582,7 +584,7 @@ class ConfigMetadata(SimpleMetadata):
     """
     def determine_metadata(self, request, view):
         # Build tree.
-        config_groups = []
+        config_groups = []  # type: List[Any] # TODO: Replace Any by correct type
         for config_variable in sorted(config.config_variables.values(), key=attrgetter('weight')):
             if config_variable.is_hidden():
                 # Skip hidden config variables. Do not even check groups and subgroups.
@@ -787,7 +789,8 @@ class VersionView(utils_views.APIView):
     http_method_names = ['get']
 
     def get_context_data(self, **context):
-        result = dict(openslides_version=version, plugins=[])
+        Result = TypedDict('Result', {'openslides_version': str, 'plugins': List[Dict[str, str]]})  # noqa
+        result = dict(openslides_version=version, plugins=[])  # type: Result
         # Versions of plugins.
         for plugin in settings.INSTALLED_PLUGINS:
             result['plugins'].append({
diff --git a/openslides/mediafiles/access_permissions.py b/openslides/mediafiles/access_permissions.py
index 455c867ce..aaf331f3c 100644
--- a/openslides/mediafiles/access_permissions.py
+++ b/openslides/mediafiles/access_permissions.py
@@ -1,4 +1,7 @@
-from ..utils.access_permissions import BaseAccessPermissions
+from ..utils.access_permissions import (  # noqa
+    BaseAccessPermissions,
+    RestrictedData,
+)
 from ..utils.auth import has_perm
 from ..utils.collection import Collection
 
@@ -41,7 +44,7 @@ class MediafileAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
diff --git a/openslides/mediafiles/models.py b/openslides/mediafiles/models.py
index ccf56b46a..c7cdfd5f6 100644
--- a/openslides/mediafiles/models.py
+++ b/openslides/mediafiles/models.py
@@ -73,7 +73,7 @@ class Mediafile(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='mediafiles/mediafile',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     def get_filesize(self):
         """
diff --git a/openslides/motions/access_permissions.py b/openslides/motions/access_permissions.py
index 35f9b4578..b60b64d06 100644
--- a/openslides/motions/access_permissions.py
+++ b/openslides/motions/access_permissions.py
@@ -1,7 +1,10 @@
 from copy import deepcopy
 
 from ..core.config import config
-from ..utils.access_permissions import BaseAccessPermissions
+from ..utils.access_permissions import (  # noqa
+    BaseAccessPermissions,
+    RestrictedData,
+)
 from ..utils.auth import has_perm
 from ..utils.collection import Collection, CollectionElement
 
@@ -78,7 +81,7 @@ class MotionAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
@@ -114,7 +117,7 @@ class MotionAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            projector_data = data
+            projector_data = data  # type: RestrictedData
         elif data:
             projector_data = data[0]
         else:
diff --git a/openslides/motions/models.py b/openslides/motions/models.py
index fd81d677b..cddd9ca79 100644
--- a/openslides/motions/models.py
+++ b/openslides/motions/models.py
@@ -231,7 +231,7 @@ class Motion(RESTModelMixin, models.Model):
             try:
                 # Always skip autoupdate. Maybe we run it later in this method.
                 with transaction.atomic():
-                    super(Motion, self).save(skip_autoupdate=True, *args, **kwargs)
+                    super(Motion, self).save(skip_autoupdate=True, *args, **kwargs)  # type: ignore
             except IntegrityError:
                 # Identifier is already used.
                 if hasattr(self, '_identifier_prefix'):
@@ -309,7 +309,7 @@ class Motion(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='motions/motion',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     def version_data_changed(self, version):
         """
@@ -879,7 +879,7 @@ class MotionBlock(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='motions/motion-block',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     @property
     def agenda_item(self):
diff --git a/openslides/motions/serializers.py b/openslides/motions/serializers.py
index 319fde060..77da86107 100644
--- a/openslides/motions/serializers.py
+++ b/openslides/motions/serializers.py
@@ -1,3 +1,5 @@
+from typing import Dict  # noqa
+
 from django.db import transaction
 from django.utils.translation import ugettext as _
 
@@ -157,7 +159,7 @@ class MotionPollSerializer(ModelSerializer):
 
     def __init__(self, *args, **kwargs):
         # The following dictionary is just a cache for several votes.
-        self._votes_dicts = {}
+        self._votes_dicts = {}  # type: Dict[int, Dict[int, int]]
         return super().__init__(*args, **kwargs)
 
     def get_yes(self, obj):
diff --git a/openslides/motions/signals.py b/openslides/motions/signals.py
index 9939c888c..79303177a 100644
--- a/openslides/motions/signals.py
+++ b/openslides/motions/signals.py
@@ -1,3 +1,5 @@
+from typing import Set  # noqa
+
 from django.apps import apps
 from django.utils.translation import ugettext_noop
 
@@ -124,7 +126,7 @@ def required_users(sender, request_user, **kwargs):
     any motion if request_user can see motions. This function may return an
     empty set.
     """
-    submitters_supporters = set()
+    submitters_supporters = set()  # type: Set[int]
     if has_perm(request_user, 'motions.can_see'):
         for motion_collection_element in Collection(Motion.get_collection_string()).element_generator():
             full_data = motion_collection_element.get_full_data()
diff --git a/openslides/motions/views.py b/openslides/motions/views.py
index ec1882e51..13b861a40 100644
--- a/openslides/motions/views.py
+++ b/openslides/motions/views.py
@@ -1,5 +1,6 @@
 import base64
 import re
+from typing import Optional  # noqa
 
 from django.conf import settings
 from django.contrib.staticfiles import finders
@@ -92,7 +93,7 @@ class MotionViewSet(ModelViewSet):
             try:
                 parent_motion = CollectionElement.from_values(
                     Motion.get_collection_string(),
-                    request.data['parent_id'])
+                    request.data['parent_id'])  # type: Optional[CollectionElement]
             except Motion.DoesNotExist:
                 raise ValidationError({'detail': _('The parent motion does not exist.')})
         else:
diff --git a/openslides/topics/models.py b/openslides/topics/models.py
index cfb2b6b41..e31478c7d 100644
--- a/openslides/topics/models.py
+++ b/openslides/topics/models.py
@@ -52,7 +52,7 @@ class Topic(RESTModelMixin, models.Model):
             skip_autoupdate=skip_autoupdate,
             name='topics/topic',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     @property
     def agenda_item(self):
diff --git a/openslides/users/access_permissions.py b/openslides/users/access_permissions.py
index a6c87c118..aa59be509 100644
--- a/openslides/users/access_permissions.py
+++ b/openslides/users/access_permissions.py
@@ -1,7 +1,12 @@
+from typing import Any, Dict, List  # noqa
+
 from django.contrib.auth.models import AnonymousUser
 
 from ..core.signals import user_data_required
-from ..utils.access_permissions import BaseAccessPermissions
+from ..utils.access_permissions import (  # noqa
+    BaseAccessPermissions,
+    RestrictedData,
+)
 from ..utils.auth import anonymous_is_enabled, has_perm
 from ..utils.collection import Collection
 
@@ -94,7 +99,7 @@ class UserAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
@@ -127,7 +132,7 @@ class UserAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            projector_data = data
+            projector_data = data  # type: RestrictedData
         elif data:
             projector_data = data[0]
         else:
@@ -187,7 +192,7 @@ class PersonalNoteAccessPermissions(BaseAccessPermissions):
 
         # Parse data.
         if user is None:
-            data = []
+            data = []  # type: List[Dict[str, Any]]
         else:
             for full in full_data:
                 if full['user_id'] == user.id:
@@ -199,7 +204,7 @@ class PersonalNoteAccessPermissions(BaseAccessPermissions):
         # Reduce result to a single item or None if it was not a collection at
         # the beginning of the method.
         if isinstance(container, Collection):
-            restricted_data = data
+            restricted_data = data  # type: RestrictedData
         elif data:
             restricted_data = data[0]
         else:
diff --git a/openslides/users/models.py b/openslides/users/models.py
index 35c55fd49..dff601ee1 100644
--- a/openslides/users/models.py
+++ b/openslides/users/models.py
@@ -220,7 +220,7 @@ class User(RESTModelMixin, PermissionsMixin, AbstractBaseUser):
             skip_autoupdate=skip_autoupdate,
             name='users/user',
             id=self.pk)
-        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)
+        return super().delete(skip_autoupdate=skip_autoupdate, *args, **kwargs)  # type: ignore
 
     def has_perm(self, perm):
         """
diff --git a/openslides/utils/access_permissions.py b/openslides/utils/access_permissions.py
index 61a1e5d5c..1bd1d8395 100644
--- a/openslides/utils/access_permissions.py
+++ b/openslides/utils/access_permissions.py
@@ -1,46 +1,29 @@
-from django.dispatch import Signal
+from typing import Any, Dict, List, Optional, Union
 
-from .collection import Collection
-from .dispatch import SignalConnectMetaClass
+from django.db.models import Model
+from rest_framework.serializers import Serializer
+
+from .collection import Collection, CollectionElement
+
+Container = Union[CollectionElement, Collection]
+RestrictedData = Union[List[Dict[str, Any]], Dict[str, Any], None]
 
 
-class BaseAccessPermissions(object, metaclass=SignalConnectMetaClass):
+class BaseAccessPermissions:
     """
     Base access permissions container.
 
     Every app which has autoupdate models has to create classes subclassing
-    from this base class for every autoupdate root model. Each subclass has
-    to have a globally unique name. The metaclass (SignalConnectMetaClass)
-    does the rest of the magic.
+    from this base class for every autoupdate root model.
     """
-    signal = Signal()
 
-    def __init__(self, **kwargs):
-        """
-        Initializes the access permission instance. This is done when the
-        signal is sent.
-
-        Because of Django's signal API, we have to take wildcard keyword
-        arguments. But they are not used here.
-        """
-        pass
-
-    @classmethod
-    def get_dispatch_uid(cls):
-        """
-        Returns the classname as a unique string for each class. Returns None
-        for the base class so it will not be connected to the signal.
-        """
-        if not cls.__name__ == 'BaseAccessPermissions':
-            return cls.__name__
-
-    def check_permissions(self, user):
+    def check_permissions(self, user: Optional[CollectionElement]) -> bool:
         """
         Returns True if the user has read access to model instances.
         """
         return False
 
-    def get_serializer_class(self, user=None):
+    def get_serializer_class(self, user: CollectionElement=None) -> Serializer:
         """
         Returns different serializer classes according to users permissions.
 
@@ -51,13 +34,13 @@ class BaseAccessPermissions(object, metaclass=SignalConnectMetaClass):
             "You have to add the method 'get_serializer_class' to your "
             "access permissions class.".format(self))
 
-    def get_full_data(self, instance):
+    def get_full_data(self, instance: Model) -> Dict[str, Any]:
         """
         Returns all possible serialized data for the given instance.
         """
         return self.get_serializer_class(user=None)(instance).data
 
-    def get_restricted_data(self, container, user):
+    def get_restricted_data(self, container: Container, user: Optional[CollectionElement]) -> RestrictedData:
         """
         Returns the restricted serialized data for the instance prepared
         for the user.
@@ -82,7 +65,7 @@ class BaseAccessPermissions(object, metaclass=SignalConnectMetaClass):
             data = None
         return data
 
-    def get_projector_data(self, container):
+    def get_projector_data(self, container: Container) -> RestrictedData:
         """
         Returns the serialized data for the projector. Returns None if the
         user has no access to this specific data. Returns reduced data if
diff --git a/openslides/utils/auth.py b/openslides/utils/auth.py
index 7984aa018..0fe46c71e 100644
--- a/openslides/utils/auth.py
+++ b/openslides/utils/auth.py
@@ -16,6 +16,7 @@ def has_perm(user: Optional[CollectionElement], perm: str) -> bool:
     group_collection_string = 'users/group'  # This is the hard coded collection string for openslides.users.models.Group
 
     # Convert user to right type
+    # TODO: Remove this and make use, that user has always the right type
     user = user_to_collection_user(user)
     if user is None and not anonymous_is_enabled():
         has_perm = False
diff --git a/openslides/utils/autoupdate.py b/openslides/utils/autoupdate.py
index 439e1dbca..e21a505e8 100644
--- a/openslides/utils/autoupdate.py
+++ b/openslides/utils/autoupdate.py
@@ -2,12 +2,14 @@ import json
 import time
 import warnings
 from collections import Iterable, defaultdict
+from typing import Any, Dict, Iterable, List, cast  # noqa
 
 from channels import Channel, Group
 from channels.asgi import get_channel_layer
 from channels.auth import channel_session_user, channel_session_user_from_http
 from django.core.exceptions import ObjectDoesNotExist
 from django.db import transaction
+from django.db.models import Model
 
 from ..core.config import config
 from ..core.models import Projector
@@ -16,7 +18,7 @@ from .cache import startup_cache, websocket_user_cache
 from .collection import Collection, CollectionElement, CollectionElementList
 
 
-def send_or_wait(send_func, *args, **kwargs):
+def send_or_wait(send_func: Any, *args: Any, **kwargs: Any) -> None:
     """
     Wrapper for channels' send() method.
 
@@ -41,7 +43,7 @@ def send_or_wait(send_func, *args, **kwargs):
         )
 
 
-def format_for_autoupdate(collection_string, id, action, data=None):
+def format_for_autoupdate(collection_string: str, id: int, action: str, data: Dict[str, Any]=None) -> Dict[str, Any]:
     """
     Returns a dict that can be used for autoupdate.
     """
@@ -64,7 +66,7 @@ def format_for_autoupdate(collection_string, id, action, data=None):
 
 
 @channel_session_user_from_http
-def ws_add_site(message):
+def ws_add_site(message: Any) -> None:
     """
     Adds the websocket connection to a group specific to the connecting user.
 
@@ -92,6 +94,9 @@ def ws_add_site(message):
         access_permissions = collection.get_access_permissions()
         restricted_data = access_permissions.get_restricted_data(collection, user)
 
+        # At this point restricted_data has to be a list. So we have to tell it mypy
+        restricted_data = cast(List[Dict[str, Any]], restricted_data)
+
         for data in restricted_data:
             if data is None:
                 # We do not want to send 'deleted' objects on startup.
@@ -100,7 +105,7 @@ def ws_add_site(message):
             output.append(
                 format_for_autoupdate(
                     collection_string=collection.collection_string,
-                    id=data['id'],
+                    id=int(data['id']),
                     action='changed',
                     data=data))
 
@@ -110,7 +115,7 @@ def ws_add_site(message):
 
 
 @channel_session_user
-def ws_disconnect_site(message):
+def ws_disconnect_site(message: Any) -> None:
     """
     This function is called, when a client on the site disconnects.
     """
@@ -119,7 +124,7 @@ def ws_disconnect_site(message):
 
 
 @channel_session_user
-def ws_receive_site(message):
+def ws_receive_site(message: Any) -> None:
     """
     This function is called if a message from a client comes in. The message
     should be a list. Every item is broadcasted to the given users (or all
@@ -137,8 +142,8 @@ def ws_receive_site(message):
     else:
         if isinstance(incomming, list):
             # Parse all items
-            receivers_users = defaultdict(list)
-            receivers_reply_channels = defaultdict(list)
+            receivers_users = defaultdict(list)  # type: Dict[int, List[Any]]
+            receivers_reply_channels = defaultdict(list)  # type: Dict[str, List[Any]]
             items_for_all = []
             for item in incomming:
                 if item.get('collection') == 'notify':
@@ -184,12 +189,12 @@ def ws_receive_site(message):
 
 
 @channel_session_user_from_http
-def ws_add_projector(message, projector_id):
+def ws_add_projector(message: Any, projector_id: int) -> None:
     """
     Adds the websocket connection to a group specific to the projector with the given id.
     Also sends all data that are shown on the projector.
     """
-    user = message.user.id
+    user = user_to_collection_user(message.user.id)
 
     if not has_perm(user, 'core.can_see_projector'):
         send_or_wait(message.reply_channel.send, {'text': 'No permissions to see this projector.'})
@@ -230,14 +235,14 @@ def ws_add_projector(message, projector_id):
             send_or_wait(message.reply_channel.send, {'text': json.dumps(output)})
 
 
-def ws_disconnect_projector(message, projector_id):
+def ws_disconnect_projector(message: Any, projector_id: int) -> None:
     """
     This function is called, when a client on the projector disconnects.
     """
     Group('projector-{}'.format(projector_id)).discard(message.reply_channel)
 
 
-def send_data(message):
+def send_data(message: Any) -> None:
     """
     Informs all site users and projector clients about changed data.
     """
@@ -285,7 +290,7 @@ def send_data(message):
                     {'text': json.dumps(output)})
 
 
-def inform_changed_data(instances, information=None):
+def inform_changed_data(instances: Iterable[Model], information: Dict[str, Any]=None) -> None:
     """
     Informs the autoupdate system and the caching system about the creation or
     update of an element.
@@ -317,7 +322,8 @@ def inform_changed_data(instances, information=None):
     transaction.on_commit(lambda: send_autoupdate(collection_elements))
 
 
-def inform_deleted_data(*args, information=None):
+# TODO: Change the input argument to tuples
+def inform_deleted_data(*args: Any, information: Dict[str, Any]=None) -> None:
     """
     Informs the autoupdate system and the caching system about the deletion of
     elements.
@@ -351,7 +357,8 @@ def inform_deleted_data(*args, information=None):
     transaction.on_commit(lambda: send_autoupdate(collection_elements))
 
 
-def inform_data_collection_element_list(collection_elements, information=None):
+def inform_data_collection_element_list(collection_elements: CollectionElementList,
+                                        information: Dict[str, Any]=None) -> None:
     """
     Informs the autoupdate system about some collection elements. This is
     used just to send some data to all users.
@@ -363,7 +370,7 @@ def inform_data_collection_element_list(collection_elements, information=None):
     transaction.on_commit(lambda: send_autoupdate(collection_elements))
 
 
-def send_autoupdate(collection_elements):
+def send_autoupdate(collection_elements: CollectionElementList) -> None:
     """
     Helper function, that sends collection_elements through a channel to the
     autoupdate system.
diff --git a/openslides/utils/cache.py b/openslides/utils/cache.py
index be801f8ca..822add703 100644
--- a/openslides/utils/cache.py
+++ b/openslides/utils/cache.py
@@ -1,10 +1,27 @@
 from collections import defaultdict
+from typing import (  # noqa
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Dict,
+    Generator,
+    Iterable,
+    List,
+    Optional,
+    Set,
+)
 
 from channels import Group
 from channels.sessions import session_for_reply_channel
 from django.apps import apps
 from django.core.cache import cache, caches
 
+if TYPE_CHECKING:
+    # Dummy import Collection for mypy
+    from .collection import Collection  # noqa
+
+UserCacheDataType = Dict[int, Set[str]]
+
 
 class BaseWebsocketUserCache:
     """
@@ -15,36 +32,36 @@ class BaseWebsocketUserCache:
     """
     cache_key = 'current_websocket_users'
 
-    def add(self, user_id, channel_name):
+    def add(self, user_id: int, channel_name: str) -> None:
         """
         Adds a channel name to an user id.
         """
         raise NotImplementedError()
 
-    def remove(self, user_id, channel_name):
+    def remove(self, user_id: int, channel_name: str) -> None:
         """
         Removes one channel name from the cache.
         """
         raise NotImplementedError()
 
-    def get_all(self):
+    def get_all(self) -> UserCacheDataType:
         """
         Returns all data using a dict where the key is a user id and the value
         is a set of channel_names.
         """
         raise NotImplementedError()
 
-    def save_data(self, data):
+    def save_data(self, data: UserCacheDataType) -> None:
         """
         Saves the full data set (like created with build_data) to the cache.
         """
         raise NotImplementedError()
 
-    def build_data(self):
+    def build_data(self) -> UserCacheDataType:
         """
         Creates all the data, saves it to the cache and returns it.
         """
-        websocket_user_ids = defaultdict(set)
+        websocket_user_ids = defaultdict(set)  # type: UserCacheDataType
         for channel_name in Group('site').channel_layer.group_channels('site'):
             session = session_for_reply_channel(channel_name)
             user_id = session.get('user_id', None)
@@ -52,7 +69,7 @@ class BaseWebsocketUserCache:
         self.save_data(websocket_user_ids)
         return websocket_user_ids
 
-    def get_cache_key(self):
+    def get_cache_key(self) -> str:
         """
         Returns the cache key.
         """
@@ -67,7 +84,7 @@ class RedisWebsocketUserCache(BaseWebsocketUserCache):
     for each user another set to save the channel names.
     """
 
-    def add(self, user_id, channel_name):
+    def add(self, user_id: int, channel_name: str) -> None:
         """
         Adds a channel name to an user id.
         """
@@ -77,35 +94,35 @@ class RedisWebsocketUserCache(BaseWebsocketUserCache):
         pipe.sadd(self.get_user_cache_key(user_id), channel_name)
         pipe.execute()
 
-    def remove(self, user_id, channel_name):
+    def remove(self, user_id: int, channel_name: str) -> None:
         """
         Removes one channel name from the cache.
         """
         redis = get_redis_connection()
         redis.srem(self.get_user_cache_key(user_id), channel_name)
 
-    def get_all(self):
+    def get_all(self) -> UserCacheDataType:
         """
         Returns all data using a dict where the key is a user id and the value
         is a set of channel_names.
         """
         redis = get_redis_connection()
-        user_ids = redis.smembers(self.get_cache_key())
+        user_ids = redis.smembers(self.get_cache_key())  # type: Optional[List[str]]
         if user_ids is None:
             websocket_user_ids = self.build_data()
         else:
             websocket_user_ids = dict()
-            for user_id in user_ids:
+            for redis_user_id in user_ids:
                 # Redis returns the id as string. So we have to convert it
-                user_id = int(user_id)
-                channel_names = redis.smembers(self.get_user_cache_key(user_id))
+                user_id = int(redis_user_id)
+                channel_names = redis.smembers(self.get_user_cache_key(user_id))  # type: Optional[List[str]]
                 if channel_names is not None:
                     # If channel name is empty, then we can assume, that the user
                     # has no active connection.
                     websocket_user_ids[user_id] = set(channel_names)
         return websocket_user_ids
 
-    def save_data(self, data):
+    def save_data(self, data: UserCacheDataType) -> None:
         """
         Saves the full data set (like created with the method build_data()) to
         the cache.
@@ -122,13 +139,13 @@ class RedisWebsocketUserCache(BaseWebsocketUserCache):
             pipe.sadd(self.get_user_cache_key(user_id), *channel_names)
         pipe.execute()
 
-    def get_cache_key(self):
+    def get_cache_key(self) -> str:
         """
         Returns the cache key.
         """
         return cache.make_key(self.cache_key)
 
-    def get_user_cache_key(self, user_id):
+    def get_user_cache_key(self, user_id: int) -> str:
         """
         Returns a cache key to save the channel names for a specific user.
         """
@@ -146,7 +163,7 @@ class DjangoCacheWebsocketUserCache(BaseWebsocketUserCache):
     the value is a set of channel names.
     """
 
-    def add(self, user_id, channel_name):
+    def add(self, user_id: int, channel_name: str) -> None:
         """
         Adds a channel name for a user using the django cache.
         """
@@ -160,7 +177,7 @@ class DjangoCacheWebsocketUserCache(BaseWebsocketUserCache):
             websocket_user_ids[user_id] = set([channel_name])
         cache.set(self.get_cache_key(), websocket_user_ids)
 
-    def remove(self, user_id, channel_name):
+    def remove(self, user_id: int, channel_name: str) -> None:
         """
         Removes one channel name from the django cache.
         """
@@ -169,7 +186,7 @@ class DjangoCacheWebsocketUserCache(BaseWebsocketUserCache):
             websocket_user_ids[user_id].discard(channel_name)
             cache.set(self.get_cache_key(), websocket_user_ids)
 
-    def get_all(self):
+    def get_all(self) -> UserCacheDataType:
         """
         Returns the data using the django cache.
         """
@@ -178,7 +195,7 @@ class DjangoCacheWebsocketUserCache(BaseWebsocketUserCache):
             return self.build_data()
         return websocket_user_ids
 
-    def save_data(self, data):
+    def save_data(self, data: UserCacheDataType) -> None:
         """
         Saves the data using the django cache.
         """
@@ -191,18 +208,18 @@ class StartupCache:
     """
     cache_key = "full_data_startup_cache"
 
-    def build(self):
+    def build(self) -> Dict[str, List[str]]:
         """
         Generate the cache by going through all apps. Returns a dict where the
         key is the collection string and the value a list of the full_data from
         the collection elements.
         """
-        cache_data = {}
+        cache_data = {}  # type: Dict[str, List[str]]
         for app in apps.get_app_configs():
             try:
                 # Get the method get_startup_elements() from an app.
                 # This method has to return an iterable of Collection objects.
-                get_startup_elements = app.get_startup_elements
+                get_startup_elements = app.get_startup_elements  # type: Callable[[], Iterable[Collection]]
             except AttributeError:
                 # Skip apps that do not implement get_startup_elements.
                 continue
@@ -216,20 +233,20 @@ class StartupCache:
         cache.set(self.cache_key, cache_data, 86400)
         return cache_data
 
-    def clear(self):
+    def clear(self) -> None:
         """
         Clears the cache.
         """
         cache.delete(self.cache_key)
 
-    def get_collections(self):
+    def get_collections(self) -> Generator['Collection', None, None]:
         """
         Generator that returns all cached Collections.
 
         The data is read from the cache if it exists. It builds the cache if it
         does not exists.
         """
-        from .collection import Collection
+        from .collection import Collection  # noqa
         data = cache.get(self.cache_key)
         if data is None:
             # The cache does not exist.
@@ -241,7 +258,7 @@ class StartupCache:
 startup_cache = StartupCache()
 
 
-def use_redis_cache():
+def use_redis_cache() -> bool:
     """
     Returns True if Redis is used als caching backend.
     """
@@ -252,7 +269,7 @@ def use_redis_cache():
     return isinstance(caches['default'], RedisCache)
 
 
-def get_redis_connection():
+def get_redis_connection() -> Any:
     """
     Returns an object that can be used to talk directly to redis.
     """
diff --git a/openslides/utils/collection.py b/openslides/utils/collection.py
index e56388a6e..2b3432d55 100644
--- a/openslides/utils/collection.py
+++ b/openslides/utils/collection.py
@@ -1,38 +1,33 @@
 from typing import Mapping  # noqa
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    Generator,
+    List,
+    Optional,
+    Set,
+    Tuple,
+    Type,
+    Union,
+)
 
 from django.apps import apps
 from django.core.cache import cache
+from django.db.models import Model
 
 from .cache import get_redis_connection, use_redis_cache
 
+if TYPE_CHECKING:
+    from .access_permissions import BaseAccessPermissions  # noqa
+
+# TODO: Try to import this type from access_permission
+RestrictedData = Union[List[Dict[str, Any]], Dict[str, Any], None]
+
 
 class CollectionElement:
-    @classmethod
-    def from_instance(cls, instance, deleted=False, information=None):
-        """
-        Returns a collection element from a database instance.
-
-        This will also update the instance in the cache.
-
-        If deleted is set to True, the element is deleted from the cache.
-        """
-        return cls(instance=instance, deleted=deleted, information=information)
-
-    @classmethod
-    def from_values(cls, collection_string, id, deleted=False, full_data=None, information=None):
-        """
-        Returns a collection element from a collection_string and an id.
-
-        If deleted is set to True, the element is deleted from the cache.
-
-        With the argument full_data, the content of the CollectionElement can be set.
-        It has to be a dict in the format that is used be access_permission.get_full_data().
-        """
-        return cls(collection_string=collection_string, id=id, deleted=deleted,
-                   full_data=full_data, information=information)
-
-    def __init__(self, instance=None, deleted=False, collection_string=None, id=None,
-                 full_data=None, information=None):
+    def __init__(self, instance: Model=None, deleted: bool=False, collection_string: str=None,
+                 id: int=None, full_data: Dict[str, Any]=None, information: Dict[str, Any]=None) -> None:
         """
         Do not use this. Use the methods from_instance() or from_values().
         """
@@ -47,7 +42,7 @@ class CollectionElement:
         elif collection_string is not None and id is not None:
             # Collection element is created via values
             self.collection_string = collection_string
-            self.id = int(id)
+            self.id = id
         else:
             raise RuntimeError(
                 'Invalid state. Use CollectionElement.from_instance() or '
@@ -65,7 +60,32 @@ class CollectionElement:
             # neither exist in the cache nor in the database.
             self.get_full_data()
 
-    def __eq__(self, collection_element):
+    @classmethod
+    def from_instance(cls, instance: Model, deleted: bool=False, information: Dict[str, Any]=None) -> 'CollectionElement':
+        """
+        Returns a collection element from a database instance.
+
+        This will also update the instance in the cache.
+
+        If deleted is set to True, the element is deleted from the cache.
+        """
+        return cls(instance=instance, deleted=deleted, information=information)
+
+    @classmethod
+    def from_values(cls, collection_string: str, id: int, deleted: bool=False,
+                    full_data: Dict[str, Any]=None, information: Dict[str, Any]=None) -> 'CollectionElement':
+        """
+        Returns a collection element from a collection_string and an id.
+
+        If deleted is set to True, the element is deleted from the cache.
+
+        With the argument full_data, the content of the CollectionElement can be set.
+        It has to be a dict in the format that is used be access_permission.get_full_data().
+        """
+        return cls(collection_string=collection_string, id=id, deleted=deleted,
+                   full_data=full_data, information=information)
+
+    def __eq__(self, collection_element: 'CollectionElement') -> bool:  # type: ignore
         """
         Compares two collection_elements.
 
@@ -75,7 +95,7 @@ class CollectionElement:
         return (self.collection_string == collection_element.collection_string and
                 self.id == collection_element.id)
 
-    def as_channels_message(self):
+    def as_channels_message(self) -> Dict[str, Any]:
         """
         Returns a dictonary that can be used to send the object through the
         channels system.
@@ -92,7 +112,7 @@ class CollectionElement:
             channel_message['full_data'] = self.full_data
         return channel_message
 
-    def as_autoupdate(self, method, *args):
+    def as_autoupdate(self, method: str, *args: Any) -> Dict[str, Any]:
         """
         Only for internal use. Do not use it directly. Use as_autoupdate_for_user()
         or as_autoupdate_for_projector().
@@ -112,19 +132,16 @@ class CollectionElement:
             action='deleted' if self.is_deleted() else 'changed',
             data=data)
 
-    def as_autoupdate_for_user(self, user):
+    def as_autoupdate_for_user(self, user: Optional['CollectionElement']) -> Dict[str, Any]:
         """
         Returns a dict that can be sent through the autoupdate system for a site
         user.
-
-        The argument `user` can be anything, that is allowd as argument for
-        utils.auth.has_perm().
         """
         return self.as_autoupdate(
             'get_restricted_data',
             user)
 
-    def as_autoupdate_for_projector(self):
+    def as_autoupdate_for_projector(self) -> Dict[str, Any]:
         """
         Returns a dict that can be sent through the autoupdate system for the
         projector.
@@ -132,22 +149,19 @@ class CollectionElement:
         return self.as_autoupdate(
             'get_projector_data')
 
-    def as_dict_for_user(self, user):
+    def as_dict_for_user(self, user: Optional['CollectionElement']) -> 'RestrictedData':
         """
         Returns a dict with the data for a user. Can be used for the rest api.
-
-        The argument `user` can be anything, that is allowd as argument for
-        utils.auth.has_perm().
         """
         return self.get_access_permissions().get_restricted_data(self, user)
 
-    def get_model(self):
+    def get_model(self) -> Type[Model]:
         """
         Returns the django model that is used for this collection.
         """
         return get_model_from_collection_string(self.collection_string)
 
-    def get_instance(self):
+    def get_instance(self) -> Model:
         """
         Returns the instance as django object.
 
@@ -165,13 +179,13 @@ class CollectionElement:
             self.instance = query.get(pk=self.id)
         return self.instance
 
-    def get_access_permissions(self):
+    def get_access_permissions(self) -> 'BaseAccessPermissions':
         """
         Returns the get_access_permissions object for the this collection element.
         """
         return self.get_model().get_access_permissions()
 
-    def get_full_data(self):
+    def get_full_data(self) -> Any:
         """
         Returns the full_data of this collection_element from with all other
         dics can be generated.
@@ -194,21 +208,21 @@ class CollectionElement:
             self.save_to_cache()
         return self.full_data
 
-    def is_deleted(self):
+    def is_deleted(self) -> bool:
         """
         Returns Ture if the item is marked as deleted.
         """
         return self.deleted
 
-    def get_cache_key(self):
+    def get_cache_key(self) -> str:
         """
         Returns a string that is used as cache key for a single instance.
         """
         return get_single_element_cache_key(self.collection_string, self.id)
 
-    def delete_from_cache(self):
+    def delete_from_cache(self) -> None:
         """
-        Delets an element from the cache.
+        Delets the element from the cache.
 
         Does nothing if the element is not in the cache.
         """
@@ -218,7 +232,7 @@ class CollectionElement:
         # Delete the id of the instance of the instance list
         Collection(self.collection_string).delete_id_from_cache(self.id)
 
-    def save_to_cache(self):
+    def save_to_cache(self) -> None:
         """
         Add or update the element to the cache.
         """
@@ -238,7 +252,7 @@ class CollectionElementList(list):
     """
 
     @classmethod
-    def from_channels_message(cls, message):
+    def from_channels_message(cls, message: Dict[str, Any]) -> 'CollectionElementList':
         """
         Creates a collection element list from a channel message.
         """
@@ -247,16 +261,16 @@ class CollectionElementList(list):
             self.append(CollectionElement.from_values(**values))
         return self
 
-    def as_channels_message(self):
+    def as_channels_message(self) -> Dict[str, Any]:
         """
         Returns a list of dicts that can be send through the channel system.
         """
-        message = {'elements': []}
+        message = {'elements': []}  # type: Dict[str, Any]
         for element in self:
             message['elements'].append(element.as_channels_message())
         return message
 
-    def as_autoupdate_for_user(self, user):
+    def as_autoupdate_for_user(self, user: Optional[CollectionElement]) -> List[Dict[str, Any]]:
         """
         Returns a list of dicts, that can be send though the websocket to a user.
 
@@ -274,7 +288,7 @@ class Collection:
     Represents all elements of one collection.
     """
 
-    def __init__(self, collection_string, full_data=None):
+    def __init__(self, collection_string: str, full_data: List[Dict[str, Any]]=None) -> None:
         """
         Initiates a Collection. A collection_string has to be given. If
         full_data (a list of dictionaries) is not given the method
@@ -284,7 +298,7 @@ class Collection:
         self.collection_string = collection_string
         self.full_data = full_data
 
-    def get_cache_key(self, raw=False):
+    def get_cache_key(self, raw: bool=False) -> str:
         """
         Returns a string that is used as cache key for a collection.
 
@@ -296,19 +310,19 @@ class Collection:
             key = cache.make_key(key)
         return key
 
-    def get_model(self):
+    def get_model(self) -> Type[Model]:
         """
         Returns the django model that is used for this collection.
         """
         return get_model_from_collection_string(self.collection_string)
 
-    def get_access_permissions(self):
+    def get_access_permissions(self) -> 'BaseAccessPermissions':
         """
         Returns the get_access_permissions object for the this collection.
         """
         return self.get_model().get_access_permissions()
 
-    def element_generator(self):
+    def element_generator(self) -> Generator[CollectionElement, None, None]:
         """
         Generator that yields all collection_elements of this collection.
         """
@@ -329,8 +343,10 @@ class Collection:
 
         # Generate collection elements that where in the cache.
         for cache_key, cached_full_data in cached_full_data_dict.items():
+            collection_string, id = get_collection_id_from_cache_key(cache_key)
             yield CollectionElement.from_values(
-                *get_collection_id_from_cache_key(cache_key),
+                collection_string,
+                id,
                 full_data=cached_full_data)
 
         # Generate collection element that where not in the cache.
@@ -343,7 +359,7 @@ class Collection:
             for instance in query.filter(pk__in=missing_ids):
                 yield CollectionElement.from_instance(instance)
 
-    def get_full_data(self):
+    def get_full_data(self) -> List[Dict[str, Any]]:
         """
         Returns a list of dictionaries with full_data of all collection
         elements.
@@ -355,7 +371,7 @@ class Collection:
                 in self.element_generator()]
         return self.full_data
 
-    def as_autoupdate_for_projector(self):
+    def as_autoupdate_for_projector(self) -> List[Dict[str, Any]]:
         """
         Returns a list of dictonaries to send them to the projector.
         """
@@ -368,12 +384,9 @@ class Collection:
             output.append(content)
         return output
 
-    def as_autoupdate_for_user(self, user):
+    def as_autoupdate_for_user(self, user: Optional[CollectionElement]) -> List[Dict[str, Any]]:
         """
         Returns a list of dicts, that can be send though the websocket to a user.
-
-        The argument `user` can be anything, that is allowd as argument for
-        utils.auth.has_perm().
         """
         # TODO: This method is not used. Remove it.
         output = []
@@ -383,22 +396,19 @@ class Collection:
                 output.append(content)
         return output
 
-    def as_list_for_user(self, user):
+    def as_list_for_user(self, user: Optional[CollectionElement]) -> List['RestrictedData']:
         """
         Returns a list of dictonaries to send them to a user, for example over
         the rest api.
-
-        The argument `user` can be anything, that is allowd as argument for
-        utils.auth.has_perm().
         """
-        output = []
+        output = []  # type: List[RestrictedData]
         for collection_element in self.element_generator():
-            content = collection_element.as_dict_for_user(user)
+            content = collection_element.as_dict_for_user(user)  # type: RestrictedData
             if content is not None:
                 output.append(content)
         return output
 
-    def get_all_ids(self):
+    def get_all_ids(self) -> Set[int]:
         """
         Returns a set of all ids of instances in this collection.
         """
@@ -408,7 +418,7 @@ class Collection:
             ids = self.get_all_ids_other()
         return ids
 
-    def get_all_ids_redis(self):
+    def get_all_ids_redis(self) -> Set[int]:
         redis = get_redis_connection()
         ids = redis.smembers(self.get_cache_key(raw=True))
         if not ids:
@@ -419,7 +429,7 @@ class Collection:
         ids = set(int(id) for id in ids)
         return ids
 
-    def get_all_ids_other(self):
+    def get_all_ids_other(self) -> Set[int]:
         ids = cache.get(self.get_cache_key())
         if ids is None:
             # If it is not in the cache then get it from the database.
@@ -427,7 +437,7 @@ class Collection:
             cache.set(self.get_cache_key(), ids)
         return ids
 
-    def delete_id_from_cache(self, id):
+    def delete_id_from_cache(self, id: int) -> None:
         """
         Delets a id from the cache.
         """
@@ -436,11 +446,11 @@ class Collection:
         else:
             self.delete_id_from_cache_other(id)
 
-    def delete_id_from_cache_redis(self, id):
+    def delete_id_from_cache_redis(self, id: int) -> None:
         redis = get_redis_connection()
         redis.srem(self.get_cache_key(raw=True), id)
 
-    def delete_id_from_cache_other(self, id):
+    def delete_id_from_cache_other(self, id: int) -> None:
         ids = cache.get(self.get_cache_key())
         if ids is not None:
             ids = set(ids)
@@ -456,7 +466,7 @@ class Collection:
                     # Delete the key, if there are not ids left
                     cache.delete(self.get_cache_key())
 
-    def add_id_to_cache(self, id):
+    def add_id_to_cache(self, id: int) -> None:
         """
         Adds a collection id to the list of collection ids in the cache.
         """
@@ -465,13 +475,13 @@ class Collection:
         else:
             self.add_id_to_cache_other(id)
 
-    def add_id_to_cache_redis(self, id):
+    def add_id_to_cache_redis(self, id: int) -> None:
         redis = get_redis_connection()
         if redis.exists(self.get_cache_key(raw=True)):
             # Only add the value if it is in the cache.
             redis.sadd(self.get_cache_key(raw=True), id)
 
-    def add_id_to_cache_other(self, id):
+    def add_id_to_cache_other(self, id: int) -> None:
         ids = cache.get(self.get_cache_key())
         if ids is not None:
             # Only change the value if it is in the cache.
@@ -480,14 +490,14 @@ class Collection:
             cache.set(self.get_cache_key(), ids)
 
 
-_models_to_collection_string = {}  # type: Mapping[str, object]
+_models_to_collection_string = {}  # type: Dict[str, Type[Model]]
 
 
-def get_model_from_collection_string(collection_string):
+def get_model_from_collection_string(collection_string: str) -> Type[Model]:
     """
     Returns a model class which belongs to the argument collection_string.
     """
-    def model_generator():
+    def model_generator() -> Generator[Type[Model], None, None]:
         """
         Yields all models of all apps.
         """
@@ -512,7 +522,7 @@ def get_model_from_collection_string(collection_string):
     return model
 
 
-def get_single_element_cache_key(collection_string, id):
+def get_single_element_cache_key(collection_string: str, id: int) -> str:
     """
     Returns a string that is used as cache key for a single instance.
     """
@@ -521,7 +531,7 @@ def get_single_element_cache_key(collection_string, id):
         id=id)
 
 
-def get_single_element_cache_key_prefix(collection_string):
+def get_single_element_cache_key_prefix(collection_string: str) -> str:
     """
     Returns the first part of the cache key for single elements, which is the
     same for all cache keys of the same collection.
@@ -529,14 +539,14 @@ def get_single_element_cache_key_prefix(collection_string):
     return "{collection}:".format(collection=collection_string)
 
 
-def get_element_list_cache_key(collection_string):
+def get_element_list_cache_key(collection_string: str) -> str:
     """
     Returns a string that is used as cache key for a collection.
     """
     return "{collection}".format(collection=collection_string)
 
 
-def get_collection_id_from_cache_key(cache_key):
+def get_collection_id_from_cache_key(cache_key: str) -> Tuple[str, int]:
     """
     Returns a tuble of the collection string and the id from a cache_key
     created with get_instance_cache_key.
diff --git a/openslides/utils/dispatch.py b/openslides/utils/dispatch.py
index 14c336fb2..bee3aa866 100644
--- a/openslides/utils/dispatch.py
+++ b/openslides/utils/dispatch.py
@@ -49,7 +49,7 @@ class SignalConnectMetaClass(type):
         default attributes and methods.
         """
         class_attributes['get_all'] = get_all
-        new_class = super(SignalConnectMetaClass, metaclass).__new__(
+        new_class = super().__new__(
             metaclass, class_name, class_parents, class_attributes)
         try:
             dispatch_uid = new_class.get_dispatch_uid()
diff --git a/openslides/utils/main.py b/openslides/utils/main.py
index 12d3862b0..4f01fb9be 100644
--- a/openslides/utils/main.py
+++ b/openslides/utils/main.py
@@ -6,10 +6,12 @@ import tempfile
 import threading
 import time
 import webbrowser
+from typing import Dict, Optional
 
 from django.conf import ENVIRONMENT_VARIABLE
 from django.core.exceptions import ImproperlyConfigured
 from django.utils.crypto import get_random_string
+from mypy_extensions import NoReturn
 
 DEVELOPMENT_VERSION = 'Development Version'
 UNIX_VERSION = 'Unix Version'
@@ -34,11 +36,11 @@ class UnknownCommand(Exception):
 
 
 class ExceptionArgumentParser(argparse.ArgumentParser):
-    def error(self, message):
+    def error(self, message: str) -> NoReturn:
         raise UnknownCommand(message)
 
 
-def detect_openslides_type():
+def detect_openslides_type() -> str:
     """
     Returns the type of this OpenSlides version.
     """
@@ -58,7 +60,7 @@ def detect_openslides_type():
     return openslides_type
 
 
-def get_default_settings_path(openslides_type=None):
+def get_default_settings_path(openslides_type: str=None) -> str:
     """
     Returns the default settings path according to the OpenSlides type.
 
@@ -80,7 +82,7 @@ def get_default_settings_path(openslides_type=None):
     return os.path.join(parent_directory, 'openslides', 'settings.py')
 
 
-def get_local_settings_path():
+def get_local_settings_path() -> str:
     """
     Returns the path to a local settings.
 
@@ -89,7 +91,7 @@ def get_local_settings_path():
     return os.path.join('personal_data', 'var', 'settings.py')
 
 
-def setup_django_settings_module(settings_path=None, local_installation=None):
+def setup_django_settings_module(settings_path: str =None, local_installation: bool=False) -> None:
     """
     Sets the environment variable ENVIRONMENT_VARIABLE, that means
     'DJANGO_SETTINGS_MODULE', to the given settings.
@@ -100,7 +102,7 @@ def setup_django_settings_module(settings_path=None, local_installation=None):
     If the argument settings_path is set, then the environment variable is
     always overwritten.
     """
-    if settings_path is None and os.environ.get(ENVIRONMENT_VARIABLE, None):
+    if settings_path is None and os.environ.get(ENVIRONMENT_VARIABLE, ""):
         return
 
     if settings_path is None:
@@ -128,7 +130,7 @@ def setup_django_settings_module(settings_path=None, local_installation=None):
     os.environ[ENVIRONMENT_VARIABLE] = settings_module_name
 
 
-def get_default_settings_context(user_data_path=None):
+def get_default_settings_context(user_data_path: str=None) -> Dict[str, str]:
     """
     Returns the default context values for the settings template:
     'openslides_user_data_path', 'import_function' and 'debug'.
@@ -154,7 +156,7 @@ def get_default_settings_context(user_data_path=None):
     return default_context
 
 
-def get_default_user_data_path(openslides_type):
+def get_default_user_data_path(openslides_type: str) -> str:
     """
     Returns the default path for user specific data according to the OpenSlides
     type.
@@ -174,7 +176,7 @@ def get_default_user_data_path(openslides_type):
     return default_user_data_path
 
 
-def get_win32_app_data_path():
+def get_win32_app_data_path() -> str:
     """
     Returns the path to Windows' AppData directory.
     """
@@ -197,7 +199,7 @@ def get_win32_app_data_path():
     return buf.value
 
 
-def get_win32_portable_path():
+def get_win32_portable_path() -> str:
     """
     Returns the path to the Windows portable version.
     """
@@ -217,14 +219,14 @@ def get_win32_portable_path():
     return portable_path
 
 
-def get_win32_portable_user_data_path():
+def get_win32_portable_user_data_path() -> str:
     """
     Returns the user data path to the Windows portable version.
     """
     return os.path.join(get_win32_portable_path(), 'openslides')
 
 
-def write_settings(settings_path=None, template=None, **context):
+def write_settings(settings_path: str=None, template: str=None, **context: str) -> str:
     """
     Creates the settings file at the given path using the given values for the
     file template.
@@ -259,7 +261,7 @@ def write_settings(settings_path=None, template=None, **context):
     return os.path.realpath(settings_path)
 
 
-def open_browser(host, port):
+def open_browser(host: str, port: int) -> None:
     """
     Launches the default web browser at the given host and port and opens
     the webinterface. Uses start_browser internally.
@@ -271,7 +273,7 @@ def open_browser(host, port):
         start_browser('http://%s:%s' % (host, port))
 
 
-def start_browser(browser_url):
+def start_browser(browser_url: str) -> None:
     """
     Launches the default web browser at the given url and opens the
     webinterface.
@@ -282,7 +284,7 @@ def start_browser(browser_url):
         print('Could not locate runnable browser: Skipping start')
     else:
 
-        def function():
+        def function() -> None:
             # TODO: Use a nonblocking sleep event here. Tornado has such features.
             time.sleep(1)
             browser.open(browser_url)
@@ -291,7 +293,7 @@ def start_browser(browser_url):
         thread.start()
 
 
-def get_database_path_from_settings():
+def get_database_path_from_settings() -> Optional[str]:
     """
     Retrieves the database path out of the settings file. Returns None,
     if it is not a SQLite3 database.
@@ -313,7 +315,7 @@ def get_database_path_from_settings():
     return database_path
 
 
-def is_local_installation():
+def is_local_installation() -> bool:
     """
     Returns True if the command is called for a local installation
 
@@ -322,7 +324,7 @@ def is_local_installation():
     return True if '--local-installation' in sys.argv or 'manage.py' in sys.argv[0] else False
 
 
-def get_geiss_path():
+def get_geiss_path() -> str:
     """
     Returns the path and file to the Geiss binary.
     """
@@ -332,7 +334,7 @@ def get_geiss_path():
     return os.path.join(download_path, bin_name)
 
 
-def is_windows():
+def is_windows() -> bool:
     """
     Returns True if the current system is Windows. Returns False otherwise.
     """
diff --git a/openslides/utils/models.py b/openslides/utils/models.py
index e9143fc1d..cc0dfc33a 100644
--- a/openslides/utils/models.py
+++ b/openslides/utils/models.py
@@ -1,3 +1,6 @@
+from typing import Any, Dict
+
+from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 
 from .access_permissions import BaseAccessPermissions  # noqa
@@ -9,11 +12,11 @@ class MinMaxIntegerField(models.IntegerField):
     IntegerField with options to set a min- and a max-value.
     """
 
-    def __init__(self, min_value=None, max_value=None, *args, **kwargs):
+    def __init__(self, min_value: int=None, max_value: int=None, *args: Any, **kwargs: Any) -> None:
         self.min_value, self.max_value = min_value, max_value
         super(MinMaxIntegerField, self).__init__(*args, **kwargs)
 
-    def formfield(self, **kwargs):
+    def formfield(self, **kwargs: Any) -> Any:
         defaults = {'min_value': self.min_value, 'max_value': self.max_value}
         defaults.update(kwargs)
         return super(MinMaxIntegerField, self).formfield(**defaults)
@@ -26,7 +29,7 @@ class RESTModelMixin:
 
     access_permissions = None  # type: BaseAccessPermissions
 
-    def get_root_rest_element(self):
+    def get_root_rest_element(self) -> models.Model:
         """
         Returns the root rest instance.
 
@@ -35,32 +38,36 @@ class RESTModelMixin:
         return self
 
     @classmethod
-    def get_access_permissions(cls):
+    def get_access_permissions(cls) -> BaseAccessPermissions:
         """
         Returns a container to handle access permissions for this model and
         its corresponding viewset.
         """
+        if cls.access_permissions is None:
+            raise ImproperlyConfigured("A RESTModel needs to have an access_permission.")
         return cls.access_permissions
 
     @classmethod
-    def get_collection_string(cls):
+    def get_collection_string(cls) -> str:
         """
         Returns the string representing the name of the collection. Returns
         None if this is not a so called root rest instance.
         """
         # TODO Check if this is a root rest element class and return None if not.
+        app_label = cls._meta.app_label  # type: ignore
+        object_name = cls._meta.object_name  # type: ignore
         return '/'.join(
-            (convert_camel_case_to_pseudo_snake_case(cls._meta.app_label),
-             convert_camel_case_to_pseudo_snake_case(cls._meta.object_name)))
+            (convert_camel_case_to_pseudo_snake_case(app_label),
+             convert_camel_case_to_pseudo_snake_case(object_name)))
 
-    def get_rest_pk(self):
+    def get_rest_pk(self) -> int:
         """
         Returns the primary key used in the REST API. By default this is
         the database pk.
         """
-        return self.pk
+        return self.pk  # type: ignore
 
-    def save(self, skip_autoupdate=False, information=None, *args, **kwargs):
+    def save(self, skip_autoupdate: bool=False, information: Dict[str, str]=None, *args: Any, **kwargs: Any) -> Any:
         """
         Calls Django's save() method and afterwards hits the autoupdate system.
 
@@ -76,12 +83,12 @@ class RESTModelMixin:
         """
         # We don't know how to fix this circular import
         from .autoupdate import inform_changed_data
-        return_value = super().save(*args, **kwargs)
+        return_value = super().save(*args, **kwargs)  # type: ignore
         if not skip_autoupdate:
             inform_changed_data(self.get_root_rest_element(), information=information)
         return return_value
 
-    def delete(self, skip_autoupdate=False, information=None, *args, **kwargs):
+    def delete(self, skip_autoupdate: bool=False, information: Dict[str, str]=None, *args: Any, **kwargs: Any) -> Any:
         """
         Calls Django's delete() method and afterwards hits the autoupdate system.
 
@@ -101,8 +108,8 @@ class RESTModelMixin:
         """
         # We don't know how to fix this circular import
         from .autoupdate import inform_changed_data, inform_deleted_data
-        instance_pk = self.pk
-        return_value = super().delete(*args, **kwargs)
+        instance_pk = self.pk  # type: ignore
+        return_value = super().delete(*args, **kwargs)  # type: ignore
         if not skip_autoupdate:
             if self != self.get_root_rest_element():
                 # The deletion of a included element is a change of the root element.
diff --git a/openslides/utils/plugins.py b/openslides/utils/plugins.py
index 9a23cd0d5..184c79de1 100644
--- a/openslides/utils/plugins.py
+++ b/openslides/utils/plugins.py
@@ -1,6 +1,7 @@
 import os
 import pkgutil
 import sys
+from typing import Any, List, Tuple
 
 from django.apps import apps
 from django.conf import settings
@@ -15,7 +16,7 @@ from openslides.utils.main import (
 
 # Methods to collect plugins.
 
-def collect_plugins_from_entry_points():
+def collect_plugins_from_entry_points() -> Tuple[str, ...]:
     """
     Collects all entry points in the group openslides_plugins from all
     distributions in the default working set and returns their module names as
@@ -24,7 +25,7 @@ def collect_plugins_from_entry_points():
     return tuple(entry_point.module_name for entry_point in iter_entry_points('openslides_plugins'))
 
 
-def collect_plugins_from_path(path):
+def collect_plugins_from_path(path: str) -> Tuple[str, ...]:
     """
     Collects all modules/packages in the given `path` and returns a tuple
     of their names.
@@ -32,7 +33,7 @@ def collect_plugins_from_path(path):
     return tuple(x[1] for x in pkgutil.iter_modules([path]))
 
 
-def collect_plugins():
+def collect_plugins() -> Tuple[str, ...]:
     """
     Collect all plugins that can be automatically discovered.
     """
@@ -52,7 +53,7 @@ def collect_plugins():
 
 # Methods to retrieve plugin metadata and urlpatterns.
 
-def get_plugin_verbose_name(plugin):
+def get_plugin_verbose_name(plugin: str) -> str:
     """
     Returns the verbose name of a plugin. The plugin argument must be a python
     dotted module path.
@@ -60,7 +61,7 @@ def get_plugin_verbose_name(plugin):
     return apps.get_app_config(plugin).verbose_name
 
 
-def get_plugin_description(plugin):
+def get_plugin_description(plugin: str) -> str:
     """
     Returns the short descrption of a plugin. The plugin argument must be a
     python dotted module path.
@@ -76,7 +77,7 @@ def get_plugin_description(plugin):
     return description
 
 
-def get_plugin_version(plugin):
+def get_plugin_version(plugin: str) -> str:
     """
     Returns the version string of a plugin. The plugin argument must be a
     python dotted module path.
@@ -92,7 +93,7 @@ def get_plugin_version(plugin):
     return version
 
 
-def get_plugin_urlpatterns(plugin):
+def get_plugin_urlpatterns(plugin: str) -> Any:
     """
     Returns the urlpatterns object for a plugin. The plugin argument must be
     a python dotted module path.
@@ -108,12 +109,12 @@ def get_plugin_urlpatterns(plugin):
     return urlpatterns
 
 
-def get_all_plugin_urlpatterns():
+def get_all_plugin_urlpatterns() -> List[Any]:
     """
     Helper function to return all urlpatterns of all plugins listed in
     settings.INSTALLED_PLUGINS.
     """
-    urlpatterns = []
+    urlpatterns = []  # type: List[Any]
     for plugin in settings.INSTALLED_PLUGINS:
         plugin_urlpatterns = get_plugin_urlpatterns(plugin)
         if plugin_urlpatterns:
diff --git a/openslides/utils/projector.py b/openslides/utils/projector.py
index b24d3ff7e..1244cbbe6 100644
--- a/openslides/utils/projector.py
+++ b/openslides/utils/projector.py
@@ -1,4 +1,4 @@
-from typing import Optional  # noqa
+from typing import Any, Dict, Iterable, List, Optional  # noqa
 
 from django.dispatch import Signal
 
@@ -18,7 +18,7 @@ class ProjectorElement(object, metaclass=SignalConnectMetaClass):
     signal = Signal()
     name = None  # type: Optional[str]
 
-    def __init__(self, **kwargs):
+    def __init__(self, **kwargs: str) -> None:
         """
         Initializes the projector element instance. This is done when the
         signal is sent.
@@ -29,15 +29,16 @@ class ProjectorElement(object, metaclass=SignalConnectMetaClass):
         pass
 
     @classmethod
-    def get_dispatch_uid(cls):
+    def get_dispatch_uid(cls) -> Optional[str]:
         """
         Returns the classname as a unique string for each class. Returns None
         for the base class so it will not be connected to the signal.
         """
         if not cls.__name__ == 'ProjectorElement':
             return cls.__name__
+        return None
 
-    def check_and_update_data(self, projector_object, config_entry):
+    def check_and_update_data(self, projector_object: Any, config_entry: Any) -> Any:
         """
         Checks projector element data via self.check_data() and updates
         them via self.update_data(). The projector object and the config
@@ -50,7 +51,7 @@ class ProjectorElement(object, metaclass=SignalConnectMetaClass):
         self.check_data()
         return self.update_data() or {}
 
-    def check_data(self):
+    def check_data(self) -> None:
         """
         Method can be overridden to validate projector element data. This
         may raise ProjectorException in case of an error.
@@ -59,7 +60,7 @@ class ProjectorElement(object, metaclass=SignalConnectMetaClass):
         """
         pass
 
-    def update_data(self):
+    def update_data(self) -> Dict[Any, Any]:
         """
         Method can be overridden to update the projector element data
         output. This should return a dictonary. Use this for server
@@ -69,21 +70,23 @@ class ProjectorElement(object, metaclass=SignalConnectMetaClass):
         """
         pass
 
-    def get_requirements(self, config_entry):
+    def get_requirements(self, config_entry: Any) -> Iterable[Any]:
         """
         Returns an iterable of instances that are required for this projector
         element. The config_entry has to be given.
         """
         return ()
 
-    def get_requirements_as_collection_elements(self, config_entry):
+    def get_requirements_as_collection_elements(self, config_entry: Any) -> Iterable[CollectionElement]:
         """
         Returns an iterable of collection elements that are required for this
         projector element. The config_entry has to be given.
         """
         return (CollectionElement.from_instance(instance) for instance in self.get_requirements(config_entry))
 
-    def get_collection_elements_required_for_this(self, collection_element, config_entry):
+    def get_collection_elements_required_for_this(
+            self, collection_element: CollectionElement,
+            config_entry: Any) -> List[CollectionElement]:
         """
         Returns a list of CollectionElements that have to be sent to every
         projector that shows this projector element according to the given
diff --git a/openslides/utils/rest_api.py b/openslides/utils/rest_api.py
index ec02e35b2..190f325f5 100644
--- a/openslides/utils/rest_api.py
+++ b/openslides/utils/rest_api.py
@@ -1,5 +1,5 @@
 from collections import OrderedDict
-from typing import Optional  # noqa
+from typing import Any, Dict, Iterable, Optional, Type  # noqa
 
 from django.http import Http404
 from rest_framework import status  # noqa
@@ -24,6 +24,7 @@ from rest_framework.serializers import (  # noqa
     ManyRelatedField,
     PrimaryKeyRelatedField,
     RelatedField,
+    Serializer,
     SerializerMethodField,
     ValidationError,
 )
@@ -31,7 +32,7 @@ from rest_framework.viewsets import GenericViewSet as _GenericViewSet  # noqa
 from rest_framework.viewsets import ModelViewSet as _ModelViewSet  # noqa
 from rest_framework.viewsets import ViewSet as _ViewSet  # noqa
 
-from .access_permissions import BaseAccessPermissions  # noqa
+from .access_permissions import BaseAccessPermissions, RestrictedData  # noqa
 from .auth import user_to_collection_user
 from .collection import Collection, CollectionElement
 
@@ -47,7 +48,7 @@ class IdManyRelatedField(ManyRelatedField):
     """
     field_name_suffix = '_id'
 
-    def bind(self, field_name, parent):
+    def bind(self, field_name: str, parent: Any) -> None:
         """
         Called when the field is bound to the serializer.
 
@@ -65,7 +66,7 @@ class IdPrimaryKeyRelatedField(PrimaryKeyRelatedField):
     """
     field_name_suffix = '_id'
 
-    def bind(self, field_name, parent):
+    def bind(self, field_name: str, parent: Any) -> None:
         """
         Called when the field is bound to the serializer.
 
@@ -80,7 +81,7 @@ class IdPrimaryKeyRelatedField(PrimaryKeyRelatedField):
         super().bind(field_name, parent)
 
     @classmethod
-    def many_init(cls, *args, **kwargs):
+    def many_init(cls, *args: Any, **kwargs: Any) -> IdManyRelatedField:
         """
         Method from rest_framework.relations.RelatedField That uses our
         IdManyRelatedField class instead of
@@ -106,7 +107,7 @@ class PermissionMixin:
     """
     access_permissions = None  # type: Optional[BaseAccessPermissions]
 
-    def get_permissions(self):
+    def get_permissions(self) -> Iterable[str]:
         """
         Overridden method to check view permissions. Returns an empty
         iterable so Django REST framework won't do any other permission
@@ -114,10 +115,10 @@ class PermissionMixin:
         and the request passes.
         """
         if not self.check_view_permissions():
-            self.permission_denied(self.request)
+            self.permission_denied(self.request)  # type: ignore
         return ()
 
-    def check_view_permissions(self):
+    def check_view_permissions(self) -> bool:
         """
         Override this and return True if the requesting user should be able to
         get access to your view.
@@ -127,22 +128,22 @@ class PermissionMixin:
         """
         return False
 
-    def get_access_permissions(self):
+    def get_access_permissions(self) -> BaseAccessPermissions:
         """
         Returns a container to handle access permissions for this viewset and
         its corresponding model.
         """
-        return self.access_permissions
+        return self.access_permissions  # type: ignore
 
-    def get_serializer_class(self):
+    def get_serializer_class(self) -> Type[Serializer]:
         """
         Overridden method to return the serializer class given by the
         access permissions container.
         """
         if self.get_access_permissions() is not None:
-            serializer_class = self.get_access_permissions().get_serializer_class(self.request.user)
+            serializer_class = self.get_access_permissions().get_serializer_class(self.request.user)  # type: ignore
         else:
-            serializer_class = super().get_serializer_class()
+            serializer_class = super().get_serializer_class()  # type: ignore
         return serializer_class
 
 
@@ -153,11 +154,11 @@ class ModelSerializer(_ModelSerializer):
     """
     serializer_related_field = IdPrimaryKeyRelatedField
 
-    def get_fields(self):
+    def get_fields(self) -> Any:
         """
         Returns all fields of the serializer.
         """
-        fields = OrderedDict()
+        fields = OrderedDict()  # type: Dict[str, Field]
 
         for field_name, field in super().get_fields().items():
             try:
@@ -177,7 +178,7 @@ class ListModelMixin(_ListModelMixin):
 
     queryset = Model.objects.all()
     """
-    def list(self, request, *args, **kwargs):
+    def list(self, request: Any, *args: Any, **kwargs: Any) -> Response:
         model = self.get_queryset().model
         try:
             collection_string = model.get_collection_string()
@@ -200,7 +201,7 @@ class RetrieveModelMixin(_RetrieveModelMixin):
 
     queryset = Model.objects.all()
     """
-    def retrieve(self, request, *args, **kwargs):
+    def retrieve(self, request: Any, *args: Any, **kwargs: Any) -> Response:
         model = self.get_queryset().model
         try:
             collection_string = model.get_collection_string()
@@ -213,7 +214,7 @@ class RetrieveModelMixin(_RetrieveModelMixin):
                 collection_string, self.kwargs[lookup_url_kwarg])
             user = user_to_collection_user(request.user)
             try:
-                content = collection_element.as_dict_for_user(user)
+                content = collection_element.as_dict_for_user(user)  # type: RestrictedData
             except collection_element.get_model().DoesNotExist:
                 raise Http404
             if content is None:
diff --git a/openslides/utils/test.py b/openslides/utils/test.py
index fd5df52cb..dd9faee8d 100644
--- a/openslides/utils/test.py
+++ b/openslides/utils/test.py
@@ -1,4 +1,5 @@
 from contextlib import ContextDecorator
+from typing import Any
 from unittest.mock import patch
 
 from django.core.cache import caches
@@ -9,7 +10,7 @@ from ..core.config import config
 
 
 class OpenSlidesDiscoverRunner(DiscoverRunner):
-    def run_tests(self, test_labels, extra_tests=None, **kwargs):
+    def run_tests(self, test_labels, extra_tests=None, **kwargs):  # type: ignore
         """
         Test Runner which does not create a database, if only unittest are run.
         """
@@ -35,7 +36,7 @@ class TestCase(_TestCase):
     Resets the config object after each test.
     """
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         config.key_to_id = {}
 
 
@@ -48,11 +49,11 @@ class use_cache(ContextDecorator):
     The code inside the contextmananger starts with an empty cache.
     """
 
-    def __enter__(self):
+    def __enter__(self) -> None:
         cache = caches['locmem']
         cache.clear()
         self.patch = patch('openslides.utils.collection.cache', cache)
         self.patch.start()
 
-    def __exit__(self, *exc):
+    def __exit__(self, *exc: Any) -> None:
         self.patch.stop()
diff --git a/openslides/utils/utils.py b/openslides/utils/utils.py
index 6983d2f3f..884e74e55 100644
--- a/openslides/utils/utils.py
+++ b/openslides/utils/utils.py
@@ -6,7 +6,7 @@ CAMEL_CASE_TO_PSEUDO_SNAKE_CASE_CONVERSION_REGEX_1 = re.compile('(.)([A-Z][a-z]+
 CAMEL_CASE_TO_PSEUDO_SNAKE_CASE_CONVERSION_REGEX_2 = re.compile('([a-z0-9])([A-Z])')
 
 
-def convert_camel_case_to_pseudo_snake_case(text):
+def convert_camel_case_to_pseudo_snake_case(text: str) -> str:
     """
     Converts camel case to pseudo snake case using hyphen instead of
     underscore.
@@ -19,12 +19,13 @@ def convert_camel_case_to_pseudo_snake_case(text):
     return CAMEL_CASE_TO_PSEUDO_SNAKE_CASE_CONVERSION_REGEX_2.sub(r'\1-\2', s1).lower()
 
 
-def to_roman(number):
+def to_roman(number: int) -> str:
     """
     Converts an arabic number within range from 1 to 4999 to the
-    corresponding roman number. Returns None on error conditions.
+    corresponding roman number. Returns the input converted as string on error
+    conditions or higher numbers.
     """
     try:
         return roman.toRoman(number)
     except (roman.NotIntegerError, roman.OutOfRangeError):
-        return None
+        return str(number)
diff --git a/openslides/utils/validate.py b/openslides/utils/validate.py
index 4413d692c..bba985dff 100644
--- a/openslides/utils/validate.py
+++ b/openslides/utils/validate.py
@@ -20,16 +20,13 @@ allowed_styles = [
 ]
 
 
-def validate_html(html):
+def validate_html(html: str) -> str:
     """
     This method takes a string and escapes all non-whitelisted html entries.
     Every field of a model that is loaded trusted in the DOM should be validated.
     """
-    if isinstance(html, str):
-        return bleach.clean(
-            html,
-            tags=allowed_tags,
-            attributes=allowed_attributes,
-            styles=allowed_styles)
-    else:
-        return html
+    return bleach.clean(
+        html,
+        tags=allowed_tags,
+        attributes=allowed_attributes,
+        styles=allowed_styles)
diff --git a/openslides/utils/views.py b/openslides/utils/views.py
index b68c4ff51..7e12932e8 100644
--- a/openslides/utils/views.py
+++ b/openslides/utils/views.py
@@ -1,12 +1,10 @@
-from typing import List  # noqa
+from typing import Any, Dict, List  # noqa
 
-from django.views import generic as django_views
 from django.views.decorators.csrf import ensure_csrf_cookie
+from django.views.generic.base import View
 from rest_framework.response import Response
 from rest_framework.views import APIView as _APIView
 
-View = django_views.View
-
 
 class CSRFMixin:
     """
@@ -14,8 +12,8 @@ class CSRFMixin:
     """
 
     @classmethod
-    def as_view(cls, *args, **kwargs):
-        view = super().as_view(*args, **kwargs)
+    def as_view(cls, *args: Any, **kwargs: Any) -> View:
+        view = super().as_view(*args, **kwargs)  # type: ignore
         return ensure_csrf_cookie(view)
 
 
@@ -32,13 +30,13 @@ class APIView(_APIView):
     http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
     """
 
-    def get_context_data(self, **context):
+    def get_context_data(self, **context: Any) -> Dict[str, Any]:
         """
         Returns the context for the response.
         """
         return context
 
-    def method_call(self, request, *args, **kwargs):
+    def method_call(self, request: Any, *args: Any, **kwargs: Any) -> Any:
         """
         Http method that returns the response object with the context data.
         """
diff --git a/setup.cfg b/setup.cfg
index ca52c6068..962096d15 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -17,8 +17,12 @@ multi_line_output = 3
 [mypy]
 ignore_missing_imports = true
 strict_optional = true
+check_untyped_defs = true
 
-[mypy-openslides.utils.auth]
+[mypy-openslides.utils.dispatch]
+ignore_errors = true
+
+[mypy-openslides.utils.*]
 disallow_any = unannotated
 
 [mypy-openslides.core.config]
diff --git a/tests/unit/utils/test_utils.py b/tests/unit/utils/test_utils.py
index f5349a3e1..6d244ddba 100644
--- a/tests/unit/utils/test_utils.py
+++ b/tests/unit/utils/test_utils.py
@@ -8,4 +8,4 @@ class ToRomanTest(TestCase):
         self.assertEqual(utils.to_roman(3), 'III')
 
     def test_to_roman_none(self):
-        self.assertTrue(utils.to_roman(-3) is None)
+        self.assertEqual(utils.to_roman(-3), '-3')