diff --git a/CHANGELOG b/CHANGELOG
index 74ce4610a..f326a1087 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -58,6 +58,7 @@ Core:
 
 Mediafiles:
 - Fixed reloading of PDF on page change [#3274].
+- Custom CKEditor plugin for browsing mediafiles [#3337].
 
 General:
 - Switched from npm to Yarn [#3188].
diff --git a/openslides/core/static/css/app.css b/openslides/core/static/css/app.css
index da95f4e76..59f0d65be 100644
--- a/openslides/core/static/css/app.css
+++ b/openslides/core/static/css/app.css
@@ -1469,6 +1469,70 @@ img {
     display: none;
 }
 
+/* image plugin for CKEditor */
+#imageBrowserContainer .imageTable {
+    table-layout: fixed;
+    width: 100%;
+}
+
+#imagePreviewSection {
+    position: absolute;
+    margin: 0px 20px 20px 20px;
+}
+
+#imagePreviewSection input {
+    width: 65px;
+}
+
+#imagePreviewSection .hidden {
+    display: none;
+}
+
+#imagePreviewSection > div {
+    margin-bottom: 10px;
+}
+
+#imagePreviewSection i {
+    font-size: 130%;
+    cursor: pointer;
+}
+
+#imagePreview {
+    max-width: 400px;
+    max-height: 300px;
+    overflow: auto;
+    padding: 2px;
+    border: 3px solid #317796;
+}
+
+#imagePreview img[src=""] {
+    display: none;
+}
+
+#imageBrowser {
+    max-height: 500px;
+    overflow: auto;
+}
+
+#imageBrowser .image {
+    position: relative;
+    float: left;
+    width: 75px;
+    height: 75px;
+    margin: 5px;
+    background-size: 125%;
+    background-repeat: no-repeat;
+    background-position: center center;
+    border: 2px solid #bed4de;
+    cursor: pointer;
+}
+#imageBrowser .image:hover {
+    border-color: #317796;
+}
+#imageBrowser .image.selected {
+    border-color: #317796;
+}
+
 /* ngDialog: override ngdialog-theme-default */
 
 .ngdialog.ngdialog-theme-default {
diff --git a/openslides/core/static/js/core/base.js b/openslides/core/static/js/core/base.js
index 56c93d570..a4d9a5e6a 100644
--- a/openslides/core/static/js/core/base.js
+++ b/openslides/core/static/js/core/base.js
@@ -855,8 +855,21 @@ angular.module('OpenSlidesApp.core', [
 .factory('Editor', [
     'gettextCatalog',
     function (gettextCatalog) {
+        var extraPlugins = [];
         return {
+            registerDialog: function (name, dialog) {
+                CKEDITOR.dialog.add(name, dialog);
+            },
+            registerPlugin: function (name, plugin) {
+                CKEDITOR.plugins.add(name, plugin);
+                extraPlugins.push(name);
+            },
             getOptions: function (images) {
+                var extraPluginsString = 'colorbutton,find,sourcedialog,justify,showblocks';
+                var registeredPluginsString = extraPlugins.join(',');
+                if (registeredPluginsString) {
+                    extraPluginsString += ',' + registeredPluginsString;
+                }
                 return {
                     on: {
                         instanceReady: function() {
@@ -930,8 +943,8 @@ angular.module('OpenSlidesApp.core', [
                         'br(os-line-break);',
 
                     // there seems to be an error in CKeditor that parses spaces in extraPlugins as part of the plugin name.
-                    extraPlugins: 'colorbutton,find,sourcedialog,justify,showblocks',
-                    removePlugins: 'wsc,scayt,a11yhelp,filebrowser,sourcearea,liststyle,tabletools,contextmenu',
+                    extraPlugins: extraPluginsString,
+                    removePlugins: 'wsc,scayt,a11yhelp,filebrowser,sourcearea,liststyle,tabletools,contextmenu,image',
                     removeButtons: 'Scayt,Anchor,Styles,HorizontalRule',
                     toolbarGroups: [
                         { name: 'clipboard', groups: [ 'clipboard', 'undo' ] },
diff --git a/openslides/mediafiles/static/js/mediafiles/image-plugin.js b/openslides/mediafiles/static/js/mediafiles/image-plugin.js
new file mode 100644
index 000000000..5ca5f2563
--- /dev/null
+++ b/openslides/mediafiles/static/js/mediafiles/image-plugin.js
@@ -0,0 +1,208 @@
+(function () {
+
+'use strict';
+
+angular.module('OpenSlidesApp.mediafiles.image-plugin', [
+    'OpenSlidesApp.mediafiles.resources',
+    'gettext',
+    'OpenSlidesApp.core',
+])
+
+.factory('ImageBrowserPlugin', [
+    '$templateCache',
+    'Mediafile',
+    'gettextCatalog',
+    'Editor',
+    function ($templateCache, Mediafile, gettextCatalog, Editor) {
+        return {
+            getPlugin: function () {
+                return {
+                    init: function (editor) {
+                        CKEDITOR.tools.imagebrowser = {};
+
+                        // Initialize this dialog, if it is opened.
+                        editor.on('dialogShow', function (event) {
+                            var dialog = event.data;
+                            if (dialog.getName() === 'imagebrowser-dialog') {
+                                CKEDITOR.dialog.getCurrent().disableButton('ok');
+
+                                // Load the main plugin template and paste it into the container
+                                var template = $templateCache.get('static/templates/mediafiles/image-plugin.html');
+                                if (!template) {
+                                    throw 'Template for image plugin not found!';
+                                }
+                                $('#imageBrowserContainer').html(template);
+
+                                // Load all images.
+                                var images = '';
+                                _.forEach(Mediafile.getAllImages(), function (image) {
+                                        images += '<div class="image" onclick="CKEDITOR.tools.imagebrowser.selectImage(\'' +
+                                            image.value + '\');" style="background-image:url(\'' +
+                                            image.value + '\');" data-image="' + image.value + '"></div>';
+                                });
+                                $('#imageBrowser').html(images);
+
+                                // Translate some strings. Angular tags are not available in CKEditor.
+                                $('#scaleLabel').html(gettextCatalog.getString('Scale'));
+
+                                // If the dialog was opened via double click, check the selected element. It
+                                // may be an image, so preselect it.
+                                var selectedElement = editor.getSelection().getStartElement();
+                                if (selectedElement.is('img')) {
+                                    // Check for given scale of this image.
+                                    var styleAttr = $(selectedElement).attr('style');
+                                    var scale;
+                                    var scaleRegex = /width\s*:\s*(\d+)\s*%/g;
+                                    var scaleMatch = scaleRegex.exec(styleAttr);
+                                    if (scaleMatch) {
+                                        scale = parseInt(scaleMatch[1]);
+                                    }
+                                    CKEDITOR.tools.imagebrowser.selectImage(
+                                        selectedElement.getAttribute('src'), scale);
+                                }
+                                // Setup event listeners.
+                                $('#image-scale').bind('keyup mouseup', function (event) {
+                                    var scale = parseInt($('#image-scale').val());
+                                    if (scale !== CKEDITOR.tools.imagebrowser.scale) {
+                                        CKEDITOR.tools.imagebrowser.updateImageSize(scale);
+                                    }
+                                });
+                            }
+                        });
+                        // React on double clicks in the textarea. If an image was selected, open this dialog.
+                        editor.on('doubleclick', function (event) {
+                            var element = event.data.element;
+                            if (!element.isReadOnly()) {
+                                if (element.is('img')) {
+                                    event.data.dialog = 'imagebrowser-dialog';
+                                    editor.getSelection().selectElement(element);
+                                }
+                            }
+                        });
+                        // Set the toolbar icon to the default image icon.
+                        CKEDITOR.on('instanceReady', function () {
+                            var toolbarIcon = $('span.cke_button_icon.cke_button__image.browser_icon');
+                            toolbarIcon.removeClass('cke_button__image browser_icon');
+                            toolbarIcon.addClass('cke_button__image_icon');
+                        });
+                        // Handler for selecting an image. It may be called by clicking on a thumbnail or by
+                        // just giving the url. The scale is optional.
+                        CKEDITOR.tools.imagebrowser.selectImage = function (url, scale) {
+                            var browser = $('#imageBrowser');
+                            _.forEach(browser.children(), function (child) { // check every available image
+                                if (child.getAttribute('data-image') == url) { //match
+                                    child.classList.add('selected');
+                                    var image = $('#imagePreview img');
+                                    // Setup an load event handler, so we can get the size of the image when loaded.
+                                    image.on('load', function (event) {
+                                        var w = event.target.naturalWidth;
+                                        var h = event.target.naturalHeight;
+                                        $('#originalSizeText').html(gettextCatalog.getString('Original size') +
+                                            ': ' + w + ' &times; ' + h );
+                                        $('#fullSizeContainer').width(w).height(h);
+                                        if (scale !== undefined) {
+                                            // Use custom scale.
+                                            CKEDITOR.tools.imagebrowser.updateImageSize(scale);
+                                        } else {
+                                            CKEDITOR.tools.imagebrowser.updateImageSize(100);
+                                        }
+                                    });
+                                    // Set the url of the main preview image.
+                                    image.attr('src', url);
+                                    $('#imagePreviewSection').removeClass('hidden');
+                                    CKEDITOR.tools.imagebrowser.selected = url;
+                                } else {
+                                    // Wrong image, deselect it in the preview window.
+                                    child.classList.remove('selected');
+                                }
+                            });
+                        };
+                        // Handler for updateing the image size.
+                        CKEDITOR.tools.imagebrowser.updateImageSize = function (scale) {
+                            if (isNaN(scale) || scale <= 0) {
+                                CKEDITOR.dialog.getCurrent().disableButton('ok');
+                            } else {
+                                CKEDITOR.dialog.getCurrent().enableButton('ok');
+                                CKEDITOR.tools.imagebrowser.scale = scale;
+                                $('#imagePreview img').width(scale + '%');
+                                $('#image-scale').val(scale);
+                            }
+                        };
+                        // Insert the selected image into the textarea.
+                        CKEDITOR.tools.imagebrowser.insertImage = function (url, scale) {
+                            var editor = CKEDITOR.currentInstance;
+                            var dialog = CKEDITOR.dialog.getCurrent();
+                            var html = '<img src="' + url + '" data-cke-saved-src="' + url +
+                                '" alt="' + url + '" style="width: ' + scale + '%;" />';
+                            editor.config.allowedContent = true;
+                            editor.insertHtml(html.trim());
+                            dialog.hide();
+                        };
+                        editor.addCommand('imagebrowser-open', new CKEDITOR.dialogCommand('imagebrowser-dialog'));
+                        editor.ui.addButton(gettextCatalog.getString('Image browser'), {
+                            label: gettextCatalog.getString('Open image browser'),
+                            command: 'imagebrowser-open',
+                            toolbar: 'insert',
+                        });
+                    },
+                };
+            },
+            getDialog: function () {
+                return function (editor) {
+                    return {
+                        title: gettextCatalog.getString('Image browser'),
+                        minWidth: 1000,
+                        minHeight: 400,
+                        contents: [
+                            {
+                                id: 'imagebrowser-tab1',
+                                label: gettextCatalog.getString('Browse for images'),
+                                elements: [
+                                    {
+                                        type: 'html',
+                                        align: 'left',
+                                        id: 'titleid',
+                                        style: 'font-size: 20px; font-weight: bold;',
+                                        html: gettextCatalog.getString('Browse for images'),
+                                    }, {
+                                        type: 'html',
+                                        align: 'left',
+                                        id: 'msg',
+                                        style: '',
+                                        html: '<div id="imageBrowserContainer"></div>'
+                                    }
+                                ],
+                            },
+                        ],
+                        // insert image on OK.
+                        onOk: function (event) {
+                            var url = CKEDITOR.tools.imagebrowser.selected;
+                            if (url) {
+                                var scale = CKEDITOR.tools.imagebrowser.scale;
+                                CKEDITOR.tools.imagebrowser.insertImage(url, scale);
+                            }
+                        },
+                    };
+                };
+            },
+        };
+    }
+])
+
+.run([
+    'Editor',
+    'ImageBrowserPlugin',
+    'gettext',
+    function (Editor, ImageBrowserPlugin, gettext) {
+        Editor.registerDialog('imagebrowser-dialog', ImageBrowserPlugin.getDialog());
+        Editor.registerPlugin('imagebrowser', ImageBrowserPlugin.getPlugin());
+
+        // mark all plugin strings
+        gettext('Original size');
+        gettext('Scale');
+        gettext('Image browser');
+        gettext('Browse for images');
+    }
+]);
+
+}());
diff --git a/openslides/mediafiles/static/js/mediafiles/site.js b/openslides/mediafiles/static/js/mediafiles/site.js
index 8eb4a33d6..cc1466875 100644
--- a/openslides/mediafiles/static/js/mediafiles/site.js
+++ b/openslides/mediafiles/static/js/mediafiles/site.js
@@ -7,6 +7,7 @@ angular.module('OpenSlidesApp.mediafiles.site', [
     'OpenSlidesApp.mediafiles.list',
     'OpenSlidesApp.mediafiles.states',
     'OpenSlidesApp.mediafiles.update',
+    'OpenSlidesApp.mediafiles.image-plugin',
 ]);
 
 }());
diff --git a/openslides/mediafiles/static/templates/mediafiles/image-plugin.html b/openslides/mediafiles/static/templates/mediafiles/image-plugin.html
new file mode 100644
index 000000000..f0f71af81
--- /dev/null
+++ b/openslides/mediafiles/static/templates/mediafiles/image-plugin.html
@@ -0,0 +1,23 @@
+<table class="imageTable">
+  <tr>
+    <td style="width: 55%; border-right: 2px solid #ddd">
+      <div id="imageBrowser"></div>
+    </td>
+    <td style="width: 45%;">
+      <div id="imagePreviewSection" class="hidden">
+        <div id="imagePreview">
+          <div id="fullSizeContainer">
+            <img src=""/>
+          </div>
+        </div>
+        <div>
+          <span id="scaleLabel"></span>
+        </div>
+        <div>
+          <input type="number" id="image-scale" class="cke_dialog_ui_input_text"> %
+        </div>
+        <div id="originalSizeText"></div>
+      </div>
+    </td>
+  </tr>
+</table>