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` `runtime.onInstalled` `scripting.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()`
script-on-click	Adds a toolbar button. Click the button to execute a script in the active tab.	`action.onClicked` `scripting.executeScript()`
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.

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