Example extensions

To illustrate how to use the WebExtensions APIs, we maintain a repository of example extensions at https://github.com/mdn/webextensions-examples. This article describes how to run these examples and lists the examples along with the WebExtensions APIs they demonstrate.

These examples work in Firefox Nightly: most work in earlier versions of Firefox, but check the strict_min_version key in the extension's manifest.json to make sure.

Warning: Some examples work only on specific domains or pages. Each example's readme file provides details of any restrictions. None of the examples work in private browsing windows by default; see Extensions in Private Browsing for details.

To try these examples, clone the repository, then install and run the extension using one of these options:

Use the Load Temporary Add-on feature and open the extension from its source folder.
Install web-ext, open the extension's source folder at the command line, and use web-ext run.

The extension stays loaded until you restart Firefox.

Warning: Don't submit these extension examples to addons.mozilla.org (AMO); you don't have to sign the examples to run them.

If you want to contribute to the repository, send us a pull request.

Name	Description	JavaScript APIs
annotate-page	Displays a sidebar that lets you take notes on web pages.	`storage.local` `tabs.onActivated` `tabs.onUpdated` `tabs.query()` `tabs.Tab` `windows.getCurrent()` `windows.Window`
apply-css	Adds a page action to the toolbar. Click the button to apply a red border using injected CSS. Click the button again to remove the CSS.	`pageAction.getTitle()` `pageAction.onClicked` `pageAction.setIcon()` `pageAction.setTitle()` `pageAction.show()` `tabs.insertCSS()` `tabs.onUpdated` `tabs.query()` `tabs.removeCSS()` `tabs.Tab`
beastify	Adds a browser action icon to the toolbar. Click the button to choose a beast. The active tab's body content is then replaced with a picture of the chosen beast.	`runtime.getURL()` `runtime.onMessage` `scripting.insertCSS()` `scripting.removeCSS()` `tabs.executeScript()` `tabs.query()` `tabs.sendMessage()` `tabs.Tab`
bookmark-it	Adds a bookmark button to the toolbar. Click the button to toggle a bookmark for the current page.	`bookmarks.create()` `bookmarks.onCreated` `bookmarks.onRemoved` `bookmarks.remove()` `bookmarks.search()` `browserAction.onClicked` `browserAction.setIcon()` `browserAction.setTitle()` `tabs.onActivated` `tabs.onUpdated` `tabs.query()` `tabs.Tab` `windows.onFocusChanged`
borderify	Adds a solid red border to all webpages matching mozilla.org.
chill-out	Show a page action after a period of inactivity. Show cat gifs when the page action is clicked.	`alarms.clearAll()` `alarms.create()` `alarms.onAlarm` `pageAction.hide()` `pageAction.onClicked` `pageAction.show()` `tabs.get()` `tabs.onActivated` `tabs.onUpdated` `tabs.query()` `tabs.update()`
commands	Demonstrates using the commands API to set up a keyboard shortcut. The shortcut created is accessed using Ctrl+Shift+U (Command+Shift+U on a Mac).	`getAll()` `onCommand` `commands.reset()` `commands.update()` `tabs.create()`
content-script-register	Illustrates how an extension can register URL-matching content scripts at runtime.	`contentScripts.register()` `runtime.onMessage` `runtime.sendMessage()`
context-menu-copy-link-with-types	Add a context menu option to links to copy the link to the clipboard, as plain text and as a link in rich HTML.	`menus.create()` `menus.onClicked` `tabs.executeScript()`
contextual-identities	List, create, and remove contextual identities.	`contextualIdentities.query()` `tabs.create()` `tabs.query()` `tabs.remove()`
cookie-bg-picker	Allows the user to customize the background color and tiled pattern on sites they visit, and also saves their preferences via a cookie, reapplying them whenever they revisit a site they previously customized.	`cookies.get()` `cookies.onChanged` `cookies.remove()` `cookies.set()` `extension.getURL()` `runtime.onMessage` `tabs.onActivated` `tabs.onUpdated` `tabs.query()` `tabs.Tab` `tabs.sendMessage()`
devtools-panels	Demonstrates some of the devtools APIs.	`devtools.inspectedWindow` `devtools.panels` `runtime.getURL()` `runtime.onMessage` `runtime.sendMessage()` `tabs.executeScript()`
discogs-search	Demonstrates adding a custom search engine with the chrome_settings_overrides key.
dnr-block-only	Demonstrates how to block network requests without host permissions using the declarativeNetRequest API with the `declarative_net_request` manifest key.	`declarativeNetRequest.Rule` `declarativeNetRequest.RuleAction` `declarativeNetRequest.RuleCondition`
dnr-dynamic-with-options	Demonstrates a generic way to request host permissions and register declarativeNetRequest rules to modify network requests, without any install-time permission warnings. The options_ui page offers a way to request permissions and register DNR rules.	`declarativeNetRequest.Rule` `declarativeNetRequest.getDynamicRules` `declarativeNetRequest.getSessionRules` `declarativeNetRequest.updateDynamicRules` `declarativeNetRequest.updateSessionRules` `permissions.getAll()` `permissions.remove()` `permissions.request()`
dnr-redirect-url	Demonstrates multiple ways to redirect requests using the declarativeNetRequest API through the `declarative_net_request` manifest key. Demonstrates aspects of Manifest Version 3 (MV3): action, host_permissions, and web_accessible_resources, and includes a comparison with Manifest Version 2 (MV2).	`declarativeNetRequest.Redirect` `declarativeNetRequest.Rule` `declarativeNetRequest.RuleAction` `declarativeNetRequest.RuleCondition` `declarativeNetRequest.URLTransform` `permissions.contains()` `permissions.remove()` `permissions.request()`
dynamic-theme	Dynamic theme example	`alarms.create()` `alarms.onAlarm` `theme.update()`
emoji-substitution	Replaces words with emojis.
eslint-example	Demonstrates how to configure an extension with eslint.
export-helpers	Demonstrates how to use export helpers like cloneInto to share objects with page scripts.	`notifications.create()` `runtime.onMessage` `runtime.sendMessage()`
favourite-colour	An example options page, letting you store your favourite colour.	`browserAction.onClicked` `runtime.openOptionsPage()` `storage.managed` `storage.sync`
find-across-tabs	Demonstration of the find API.	`browserAction.onClicked` `extension.getBackgroundPage()` `find.find()` `find.highlightResults()` `runtime.getURL()` `runtime.onMessage` `runtime.sendMessage()` `tabs.create()` `tabs.query()` `tabs.Tab`
firefox-code-search	Demonstrates how to use the omnibox API.	`omnibox.onInputChanged` `omnibox.onInputEntered` `omnibox.setDefaultSuggestion()` `tabs.create()` `tabs.update()`
forget-it	Demonstrates how to use the browsingData API.	`browserAction.onClicked` `browsingData.remove()` `notifications.create()` `storage.local`
google-userinfo	Demonstrates how to use the identity API.	`browserAction.onClicked` `identity.getRedirectURL()` `identity.launchWebAuthFlow` `notifications.create()`
history-deleter	History API demo: deletes history items for a given domain	`history.deleteUrl()` `history.search()` `pageAction.show()` `tabs.onUpdated` `tabs.query()`
http-response	Demonstrates how to rewrite HTTP responses using the webRequest.filterResponseData() API.	`webRequest.filterResponseData()` `webRequest.onBeforeRequest`
imagify	Using a sidebar, illustrates the use of file picker and drag and drop. A content script replaces the current page content with the chosen image.	`extension.getURL()` `runtime.onMessage` `tabs.executeScript()` `tabs.query()` `tabs.sendMessage()`
latest-download	Shows the last downloaded item, and lets you open or delete it.	`downloads.erase()` `downloads.getFileIcon()` `downloads.open()` `downloads.removeFile()` `downloads.search()`
list-cookies	This extensions list the cookies in the active tab.	`cookies.getAll()` `tabs.query()`
menu-accesskey-visible	Shows how to set up a single letter access key for a menu item.	`i18n.getMessage()` `menus.update()` `menus.create()` `menus.onClicked`
menu-demo	Demonstrates adding and manipulating menu items using the menus API.	`i18n.getMessage()` `menus.create()` `menus.onClicked` `menus.remove()` `menus.update()` `runtime.lastError` `tabs.executeScript()`
menu-labelled-open	Shows how an extension can listen for the display of a menu and then add, remove, or update its menu items.	`menus.create()` `menus.onClicked` `menus.onShown` `menus.refresh()` `menus.update()` `tabs.update()`
menu-remove-element	Shows how to detect the page element at the cursor position and remove that element, or a parent element, from the page. This example includes use of the polyfill, illustrating cross-browser extension development.	`menus.create()` `menus.onClicked` `menus.getTargetElement()` `pageAction.openPopup()` `pageAction.show()` `tabs.executeScript()`
menu-search	Illustrates how to retrieve a list of search engines and issue a search request, using search engine details added to the context menu for selected text.	`search.search()` `search.get()` `menus.create()` `menus.onClicked`
mocha-client-tests	This example shows two methods of testing an extension: running tests from within the extension, and running tests from the command line using Karma.	`runtime.onMessage` `runtime.sendMessage()`
native-messaging	Example of native messaging, including a Python application and an extension which exchanges messages with it.	`browserAction.onClicked` `runtime.connectNative()`
navigation-stats	Demonstration of the webNavigation API, showing basic stats about which pages you've visited.	`storage.local` `webNavigation.onCommitted` `webNavigation.onCompleted`
notify-link-clicks-i18n	Shows a localized notification when the user clicks on links.	`extension.getURL()` `i18n.getMessage()` `notifications.create()` `runtime.onMessage` `runtime.sendMessage()`
open-my-page-button	Adds a browser action icon to the toolbar. When the browser action is clicked, the add-on opens a page that was packaged with it.	`browserAction.onClicked` `tabs.create()`
page-to-extension-messaging	Demonstrates how a web page and a content script can exchange messages. Visit https://mdn.github.io/webextensions-examples/content-script-page-script-messaging.html for the demo.
permissions	Demonstrates optional permissions using the permissions API.	`browserAction.onClicked` `permissions.getAll()` `permissions.remove()` `permissions.request()` `runtime.getURL()` `tabs.create()`
private-browsing-theme	Example dynamic theme: sets a dark theme for private windows.	`theme.reset()` `theme.update()` `windows.getAll()` `windows.onCreated`
proxy-blocker	Uses the proxy API to block requests to hosts specified on a list.	`extension.getURL()` `proxy.onRequest` `proxy.onError` `storage.local` `storage.onChanged`
quicknote	Allows the user to make quick notes by clicking a button and entering text into the resulting popup. The notes are saved in storage.	`storage.local`
root-cert-stats	Shows how to get details about a request's TLS connection.	`webRequest.getSecurityInfo()`
runtime-examples	Demo of various runtime APIs.	`browserAction.onClicked` `notifications.create()` `runtime.getManifest()` `runtime.onInstalled` `runtime.reload()`
selection-to-clipboard	Demonstrates how to write to the clipboard from a content script
session-state	Demonstrates how to retrieve extension-defined state from restored tabs.	`menus.create()` `menus.onClicked` `sessions.getTabValue()` `sessions.setTabValue()` `tabs.insertCSS()` `tabs.onCreated` `tabs.onUpdated` `tabs.query()`
store-collected-images	Demonstrates how to use the idb-file-storage library to store and manipulate files in an extension.	`browserAction.onClicked` `menus.create()` `menus.onClicked` `runtime.onMessage` `runtime.sendMessage()` `tabs.create()` `windows.create()`
stored-credentials	Performs basic authentication by supplying stored credentials.	`storage.local` `webRequest.onAuthRequired` `webRequest.onCompleted` `webRequest.onErrorOccurred`
tabs-tabs-tabs	Demonstrates tab manipulation: opening, closing, moving, zooming tabs.	`browserAction.setBadgeBackgroundColor()` `browserAction.setBadgeText()` `tabs.create()` `tabs.duplicate()` `tabs.getZoom()` `tabs.move()` `tabs.onCreated` `tabs.onMoved` `tabs.onRemoved` `tabs.query()` `tabs.reload()` `tabs.remove()` `tabs.setZoom()` `tabs.Tab` `tabs.update()`
theme-integrated-sidebar	A sidebar that integrates with the current theme.	`theme.getCurrent()` `theme.onUpdated` `windows.getCurrent()`
theme-switcher	An example of how to use the management API for themes.	`management.getAll()` `management.setEnabled()`
themed-icons	Demonstration of how to use the `prefers-color-scheme` media query to adapt an SVG icon to dark and light themes.	`runtime.getURL()` `tabs.query()` `tabs.create()` `tabs.update()` `management.getAll()` `management.setEnabled()` `management.onEnabled()` `pageAction.onClicked` `action.onClicked`
themes	A collection of themes illustrating: weta_fade: a basic theme employing a single image specified in `theme_frame:`. weta_fade_chrome: the weta_fade theme implemented with Chrome compatible manifest keys. weta_tiled: a theme using a tiled image. weta_mirror: a theme using multiple images and aligning those images in the header. animated: use of an animated PNG.
top-sites	Demonstration of the topSites API.	`topSites.get()`
user-agent-rewriter	Demonstrates using the webRequest API to rewrite the User-Agent HTTP header.	`extension.getBackgroundPage()` `webRequest.onBeforeSendHeaders`
user-script-register	Illustrates how an extension can register URL-matching user scripts at runtime (Manifest Version 2 only).	`userScripts.register() (Legacy)` `runtime.onMessage` `runtime.sendMessage()`
userScripts-mv3	A user script manager demonstrating the userScripts API, permissions API, optional_permissions, and Manifest Version 3 (MV3).	`userScripts.configureWorld()` `userScripts.getScripts()` `userScripts.register()` `userScripts.resetWorldConfiguration()` `userScripts.unregister()` `userScripts.update()` `permissions.onAdded` `permissions.onRemoved` `permissions.request()` `runtime.onInstalled` `runtime.onMessage` `runtime.onUserScriptMessage` `runtime.openOptionsPage()` `runtime.sendMessage()` `storage.local` `storage.onChanged` `storage.session`
webpack-modules	Demonstrates how to use webpack to package npm modules in an extension.	`runtime.onMessage` `runtime.sendMessage()`
window-manipulator	Demonstrates how to manipulate windows: opening, closing, resizing windows.	`windows.create()` `windows.getAll()` `windows.getCurrent()` `windows.remove()` `windows.update()` `windows.Window`
open-irc-links	Demonstrates the use of protocol handlers.

Help improve MDN

Learn how to contribute

This page was last modified on Mar 22, 2026 by MDN contributors.

View this page on GitHub • Report a problem with this content