diff --git a/.eslintrc.js b/.eslintrc.js
index 3dfcb35b..fc6244b7 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -44,10 +44,7 @@ module.exports = {
         "editor/redirect-on-no-module-support.js",
         "editor/extensions/imagelib/index.js",
         "editor/external/dom-polyfill/dom-polyfill.js",
-        "screencasts/svgopen2010/script.js",
-        "opera-widget/handlers.js",
-        "firefox-extension/handlers.js",
-        "firefox-extension/content/svg-edit-overlay.js"
+        "screencasts/svgopen2010/script.js"
       ],
       rules: {
         "import/unambiguous": ["off"]
@@ -223,15 +220,6 @@ module.exports = {
         ]
       }
     },
-    {
-      // Misc. probably to remove
-      files: ['firefox-extension/**', 'opera-widget/**'],
-      settings: {
-        polyfills: [
-          'console'
-        ]
-      }
-    },
     {
       files: ["cypress/**"],
       extends: ["plugin:cypress/recommended"],
diff --git a/CHANGES.md b/CHANGES.md
index 17933323..a34e31e6 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -24,6 +24,9 @@
     `url` is set within the URL)
 - Optimization: Remove unused `jquery-ui-1.8.custom.min.js` file
 - Optimization: Remove old build/tools closure/yuicompressor code
+- Optimization: Remove unmaintained chrome-app, firefox-extension,
+  opera-widget (an updated WebExtensions replacement (or such)
+  would be welcome.)
 - Localization: Add 'SVG-Edit Home Page' to locale files
 - Docs: Remove outdated info on jsdoc linting (now just part of eslint config)
 - Docs: Add testing badge
diff --git a/chrome-app/icon_128.png b/chrome-app/icon_128.png
deleted file mode 100644
index 6369b49b..00000000
Binary files a/chrome-app/icon_128.png and /dev/null differ
diff --git a/chrome-app/manifest.json b/chrome-app/manifest.json
deleted file mode 100644
index 80dba56d..00000000
--- a/chrome-app/manifest.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-  "name": "SVG-edit",
-  "description": "A fast, web-based, Javascript-driven SVG editor that works in any modern browser",
-  "version": "2.6",
-  "app": {
-    "urls": [
-      "*://svg-edit.googlecode.com/svn/tags/stable/"
-    ],
-    "launch": {
-      "web_url": "http://svg-edit.googlecode.com/svn/tags/stable/editor/svg-editor.html"
-    }
-  },
-  "icons": {
-    "128": "icon_128.png"
-  },
-  "permissions": [
-    "unlimitedStorage",
-    "notifications"
-  ]
-}
diff --git a/docs/jsdoc-config.js b/docs/jsdoc-config.js
index ac1b4001..f4941e7a 100644
--- a/docs/jsdoc-config.js
+++ b/docs/jsdoc-config.js
@@ -61,8 +61,6 @@ module.exports = {
       'node_modules',
       'dist',
       'editor/external',
-      'firefox-extension',
-      'opera-widget',
       'screencasts',
       'test'
     ],
diff --git a/firefox-extension/chrome.manifest b/firefox-extension/chrome.manifest
deleted file mode 100644
index 3e98b2dd..00000000
--- a/firefox-extension/chrome.manifest
+++ /dev/null
@@ -1,2 +0,0 @@
-content	svg-edit	content/
-overlay	chrome://browser/content/browser.xul	chrome://svg-edit/content/svg-edit-overlay.xul
diff --git a/firefox-extension/content/svg-edit-overlay.css b/firefox-extension/content/svg-edit-overlay.css
deleted file mode 100644
index 4b7e9b54..00000000
--- a/firefox-extension/content/svg-edit-overlay.css
+++ /dev/null
@@ -1,21 +0,0 @@
-#svg-edit-statusbar-button {
-  list-style-image: url("chrome://svg-edit/content/editor/images/logo.png");
-  display: -moz-box;
-  /*-moz-image-region: rect(16px, 16px, 32px, 0px);*/
-  padding-left: 0px;
-  padding-right: 0px;
-  width: 16px;
-  height: 16px;
-
-}
-
-#svg-edit-statusbar-button[state="active"] { 
-  list-style-image: url("chrome://svg-edit/content/editor/images/logo.png");
-  -moz-image-region: rect(32px, 16px, 48px, 0px);
-}
-
-#svg-edit-statusbar-button[state="error"] {
-  list-style-image: url("chrome://svg-edit/content/editor/images/logo.png");
-  -moz-image-region: rect(0px, 16px, 16px, 0px);
-}
-
diff --git a/firefox-extension/content/svg-edit-overlay.js b/firefox-extension/content/svg-edit-overlay.js
deleted file mode 100644
index 0c05a594..00000000
--- a/firefox-extension/content/svg-edit-overlay.js
+++ /dev/null
@@ -1,8 +0,0 @@
-/**
- * Opens the dialog with the SVG Editor.
- * @returns {void}
- */
-function startSvgEdit () { // eslint-disable-line no-unused-vars
-  const url = 'chrome://svg-edit/content/editor/svg-editor.html';
-  window.openDialog(url, 'SVG Editor', 'width=1024,height=700,menubar=no,toolbar=no');
-}
diff --git a/firefox-extension/content/svg-edit-overlay.xul b/firefox-extension/content/svg-edit-overlay.xul
deleted file mode 100644
index ac8899c3..00000000
--- a/firefox-extension/content/svg-edit-overlay.xul
+++ /dev/null
@@ -1,25 +0,0 @@
-<?xml version="1.0"?>
-
-<?xml-stylesheet href="chrome://svg-edit/content/svg-edit-overlay.css" type="text/css"?>
-
-<!DOCTYPE overlay SYSTEM "chrome://chromelist/locale/ChromeListOverlay.dtd" >
-<overlay id="SVGEditToolsOverlay"
-        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
-
-<script type="application/x-javascript"
-       src="chrome://svg-edit/content/svg-edit-overlay.js" />
-
-<menupopup id="menu_ToolsPopup">
-       <menuitem insertafter="devToolsSeparator" label="SVG Editor"
-       oncommand="startSvgEdit();" />
-</menupopup>
-
- <!-- Firefox -->
-  <statusbar id="status-bar">
-    <statusbarpanel id="svg-edit-statusbar-button"
-        class="statusbarpanel-menu-iconic"
-        onclick="return startSvgEdit()"
-        tooltip="SvgEdit">
-    </statusbarpanel>
- </statusbar>
-</overlay>
diff --git a/firefox-extension/handlers.js b/firefox-extension/handlers.js
deleted file mode 100644
index d33cb0ec..00000000
--- a/firefox-extension/handlers.js
+++ /dev/null
@@ -1,60 +0,0 @@
-/* global svgCanvas, jQuery, Components, netscape */
-// Note: This JavaScript file must be included as the last script on the main HTML editor page to override the open/save handlers
-jQuery(function () {
-  if (!window.Components) return;
-
-  /**
-   * Offer choice of file.
-   * @param {boolean} readflag
-   * @returns {nsILocalFile}
-   */
-  function mozFilePicker (readflag) {
-    const fp = window.Components.classes['@mozilla.org/filepicker;1']
-      .createInstance(Components.interfaces.nsIFilePicker);
-    if (readflag) fp.init(window, 'Pick a SVG file', fp.modeOpen);
-    else fp.init(window, 'Pick a SVG file', fp.modeSave);
-    fp.defaultExtension = '*.svg';
-    fp.show();
-    return fp.file;
-  }
-
-  svgCanvas.setCustomHandlers({
-    open () {
-      try {
-        netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');
-        const file = mozFilePicker(true);
-        if (!file) {
-          return;
-        }
-
-        const inputStream = Components.classes['@mozilla.org/network/file-input-stream;1'].createInstance(Components.interfaces.nsIFileInputStream);
-        inputStream.init(file, 0x01, 0o00004, null);
-        const sInputStream = Components.classes['@mozilla.org/scriptableinputstream;1'].createInstance(Components.interfaces.nsIScriptableInputStream);
-        sInputStream.init(inputStream);
-        svgCanvas.setSvgString(sInputStream.read(sInputStream.available()));
-      } catch (e) {
-        console.log('Exception while attempting to load' + e); // eslint-disable-line no-console
-      }
-    },
-    save (svg, str) {
-      try {
-        const file = mozFilePicker(false);
-        if (!file) {
-          return;
-        }
-
-        if (!file.exists()) {
-          file.create(0, 0o0664);
-        }
-
-        const out = Components.classes['@mozilla.org/network/file-output-stream;1'].createInstance(Components.interfaces.nsIFileOutputStream);
-        out.init(file, 0x20 | 0x02, 0o00004, null); // eslint-disable-line no-bitwise
-        out.write(str, str.length);
-        out.flush();
-        out.close();
-      } catch (e) {
-        alert(e); // eslint-disable-line no-alert
-      }
-    }
-  });
-});
diff --git a/firefox-extension/install.rdf b/firefox-extension/install.rdf
deleted file mode 100644
index 781b80ad..00000000
--- a/firefox-extension/install.rdf
+++ /dev/null
@@ -1,21 +0,0 @@
-<?xml version="1.0"?>
-
-<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
-     xmlns:em="http://www.mozilla.org/2004/em-rdf#">
-  <Description about="urn:mozilla:extension:file:chrome"
-                   em:package="content" />
-  <Description about="urn:mozilla:install-manifest">
-    <!-- required properties -->
-    <em:id>svg-edit@googlegroups.com</em:id>
-    <em:version>2.6</em:version>
-    <em:type>2</em:type>
-    <em:targetApplication>
-      <Description>
-        <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
-        <em:minVersion>1.5</em:minVersion>
-        <em:maxVersion>4.*</em:maxVersion>
-      </Description>
-    </em:targetApplication>
-    <em:name>SVG-edit</em:name>
-  </Description>
-</RDF>
diff --git a/opera-widget/config.xml b/opera-widget/config.xml
deleted file mode 100644
index 797aafba..00000000
--- a/opera-widget/config.xml
+++ /dev/null
@@ -1,17 +0,0 @@
-<?xml version="1.0"?>
-<widget defaultmode="application">
-  <widgetname>SVG Edit</widgetname>
-  <description>
-    A simple SVG Editor.
-  </description>
-  <width>800</width>
-  <height>600</height>
-  <icon>editor/images/logo.svg</icon>
-  <id>
-    <name>SVG Edit</name>
-    <revised>2010-09</revised>
-  </id>
-  <feature name="http://xmlns.opera.com/fileio">
-    <param name="folderhint" value="home" />
-  </feature>
-</widget>
diff --git a/opera-widget/handlers.js b/opera-widget/handlers.js
deleted file mode 100644
index e5d2a549..00000000
--- a/opera-widget/handlers.js
+++ /dev/null
@@ -1,60 +0,0 @@
-/* globals jQuery, svgCanvas */
-/* eslint-disable no-console */
-// Note: This JavaScript file must be included as the last script on the main
-//  HTML editor page to override the open/save handlers
-jQuery(function () {
-  if (window.opera && window.opera.io && window.opera.io.filesystem) {
-    svgCanvas.setCustomHandlers({
-      open () {
-        try {
-          window.opera.io.filesystem.browseForFile(
-            new Date().getTime(), /* mountpoint name */
-            '', /* default location */
-            function (file) {
-              try {
-                if (file) {
-                  const fstream = file.open(file, 'r');
-                  let output = '';
-                  while (!fstream.eof) {
-                    output += fstream.readLine();
-                  }
-
-                  svgCanvas.setSvgString(output); /* 'this' is bound to the filestream object here */
-                }
-              } catch (e) {
-                console.log('Reading file failed.');
-              }
-            },
-            false, /* not persistent */
-            false, /* no multiple selections */
-            '*.svg' /* file extension filter */
-          );
-        } catch (e) {
-          console.log('Open file failed.');
-        }
-      },
-      save (win, svg) {
-        try {
-          win.opera.io.filesystem.browseForSave(
-            new Date().getTime(), /* mountpoint name */
-            '', /* default location */
-            function (file) {
-              try {
-                if (file) {
-                  const fstream = file.open(file, 'w');
-                  fstream.write(svg, 'UTF-8');
-                  fstream.close();
-                }
-              } catch (e) {
-                console.log('Write to file failed.');
-              }
-            },
-            false /* not persistent */
-          );
-        } catch (e) {
-          console.log('Save file failed.');
-        }
-      }
-    });
-  }
-});
diff --git a/opera-widget/index.html b/opera-widget/index.html
deleted file mode 100644
index 4d5e292c..00000000
--- a/opera-widget/index.html
+++ /dev/null
@@ -1,28 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <meta charset="utf-8" />
-    <title>SVG Edit</title>
-    <link rel="stylesheet" href="style.css">
-    <script>
-      /* eslint-disable no-unused-vars */
-      /**
-       * This method adds the script that overrides the default open/save handlers.
-       * @returns {void}
-       */
-      function addHandlers () {
-        const cdoc = document.getElementById('container').contentDocument;
-        if (cdoc) {
-          const scriptelm = cdoc.createElement('script');
-          scriptelm.src = '../handlers.js';
-          cdoc.getElementsByTagName('head')[0].appendChild(scriptelm);
-        }
-      }
-    </script>
-  </head>
-  <body>
-    <object id="container" data="editor/svg-editor.html" onload="addHandlers()">
-      Failed to load for some reason.
-    </object>
-  </body>
-</html>
diff --git a/opera-widget/style.css b/opera-widget/style.css
deleted file mode 100644
index b4e8ae66..00000000
--- a/opera-widget/style.css
+++ /dev/null
@@ -1,2 +0,0 @@
-body { margin: 0px; padding: 0px; }
-#container { width: 100%; height: 100%; border: none; }
diff --git a/package.json b/package.json
index c1508bd2..e380a961 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "open-docs-no-start": "open-cli http://localhost:8000/docs/jsdoc/",
     "open-docs": "run-p start open-docs-no-start",
     "build-html": "npx babel-node --plugins @babel/plugin-transform-modules-commonjs build/build-html.js",
-    "compress-images": "imageoptim \"chrome-app/*.png\" \"editor/extensions/*.png\" \"editor/spinbtn/*.png\" \"editor/jgraduate/images/*.{png,gif}\" \"editor/images/*.png\"",
+    "compress-images": "imageoptim \"editor/extensions/*.png\" \"editor/spinbtn/*.png\" \"editor/jgraduate/images/*.{png,gif}\" \"editor/images/*.png\"",
     "copy": "copyfiles -f node_modules/load-stylesheets/dist/index-es.js editor/external/load-stylesheets && copyfiles -f node_modules/jamilih/dist/jml-es.js editor/external/jamilih && copyfiles -f node_modules/query-result/esm/index.js editor/external/query-result/esm && copyfiles -f node_modules/qr-manipulation/dist/index-es.js editor/external/qr-manipulation/dist && copyfiles -f node_modules/stackblur-canvas/dist/stackblur-es.js editor/external/stackblur-canvas/dist && copyfiles -f node_modules/regenerator-runtime/runtime.js editor/external/regenerator-runtime && copyfiles -f \"node_modules/core-js-bundle//minified*\" editor/external/core-js-bundle && copyfiles -f \"node_modules/underscore/underscore-*\" editor/jspdf && copyfiles -f \"node_modules/deparam/dist/deparam.esm.js\" editor/external/deparam",
     "remark": "remark -q -f .",
     "eslint-fix": "eslint --fix --ext js,md,html .",