JavaScript APIs


Schedule code to run at a specific time in the future. This is like setTimeout() and setInterval(), except that those functions don't work with background pages that are loaded on demand.

Chrome: 7/7 Edge: 0/7 Firefox: 7/7 Firefox for Android: 7/7 Opera: 7/7

API reference documentation


The WebExtensions bookmarks API lets an add-on interact with and manipulate the browser's bookmarking system. You can use it to bookmark pages, retrieve existing bookmarks, and edit, remove, and organize bookmarks.

Chrome: 23/23 Edge: 0/23 Firefox: 14/23 Firefox for Android: 0/23 Opera: 23/23

API reference documentation


If you specify a popup, it will be shown — and the content will be loaded — when the user clicks the icon. If you do not specify a popup, then when the user clicks the icon an event is dispatched to your extension.

Chrome: 14/14 Edge: 10/14 Firefox: 14/14 Firefox for Android: 0/14 Opera: 14/14

API reference documentation


Listen for the user executing commands that you have registered using the commands manifest.json key.

Chrome: 3/3 Edge: 0/3 Firefox: 3/3 Firefox for Android: 0/3 Opera: 3/3

API reference documentation


Add items to the browser's context menu, to be displayed in the contexts you specify. For example, you can show the item only when the user clicks on an image, or on an editable element, or when part of a page is selected.

Chrome: 9/9 Edge: 9/9 Firefox: 9/9 Firefox for Android: 0/9 Opera: 9/9

API reference documentation


Enables WebExtensions to get and set cookies, and be notified when they change.

Chrome: 9/9 Edge: 7/9 Firefox: 9/9 Firefox for Android: 9/9 Opera: 9/9

API reference documentation


Enables WebExtensions to interact with the browser's download manager. You can use this API module to download files, cancel, pause, resume downloads, and show downloaded files in the file manager.

Chrome: 27/27 Edge: 0/27 Firefox: 23/27 Firefox for Android: 23/27 Opera: 27/27

API reference documentation


Common types used by APIs that dispatch events.

Chrome: 3/3 Edge: 3/3 Firefox: 1/3 Firefox for Android: 1/3 Opera: 3/3

API reference documentation


Utilities related to your add-on. Get URLs to resources packages with your add-on, get the Window object for your add-on's pages, get the values for various settings. Note that the messaging APIs in this module are deprecated in favor of the equivalent APIs in the runtime module.

Chrome: 13/13 Edge: 2/13 Firefox: 8/13 Firefox for Android: 8/13 Opera: 11/13

API reference documentation


Some common types used in other WebExtension APIs.

Chrome: 4/4 Edge: 4/4 Firefox: 4/4 Firefox for Android: 4/4 Opera: 3/4

API reference documentation


Use the history API to interact with the browser history.

Chrome: 11/11 Edge: 0/11 Firefox: 11/11 Firefox for Android: 0/11 Opera: 11/11

API reference documentation


Functions to internationalize your add-on. You can use these APIs to get localized strings from locale files packaged with your add-on, find out the browser's current language, and find out the value of its Accept-Language header.

Chrome: 5/5 Edge: 4/5 Firefox: 5/5 Firefox for Android: 5/5 Opera: 4/5

API reference documentation


Find out when the user's system is idle, locked, or active.

Chrome: 4/4 Edge: 0/4 Firefox: 2/4 Firefox for Android: 2/4 Opera: 4/4

API reference documentation


This API provides ways to manage the list of extensions that are installed and running.

Chrome: 13/13 Edge: 0/13 Firefox: 3/13 Firefox for Android: 3/13 Opera: 12/13

API reference documentation


Display notifications to the user, using the underlying operating system's notification mechanism. Because this API uses the operating system's notification mechanism, the details of how notifications appear and behave may differ according to the operating system and the user's settings.

Chrome: 9/9 Edge: 0/9 Firefox: 7/9 Firefox for Android: 7/9 Opera: 9/9

API reference documentation


A page action is a clickable icon inside the browser's address bar.

Chrome: 9/9 Edge: 8/9 Firefox: 9/9 Firefox for Android: 5/9 Opera: 9/9

API reference documentation


This module provides information about your add-on and the environment it's running in.

Chrome: 35/35 Edge: 10/35 Firefox: 24/35 Firefox for Android: 22/35 Opera: 35/35

API reference documentation


Enables WebExtensions to store and retrieve data, and listen for changes to stored items.

Chrome: 11/11 Edge: 9/11 Firefox: 8/11 Firefox for Android: 8/11 Opera: 9/11

API reference documentation


Interact with the browser's tab system.

Chrome: 45/46 Edge: 18/46 Firefox: 40/46 Firefox for Android: 0/46 Opera: 37/46

API reference documentation


Add event listeners for the various stages of a navigation. A navigation consists of a frame in the browser transitioning from one URL to another, usually (but not always) in response to a user action like clicking a link or entering a URL in the location bar.

Chrome: 13/13 Edge: 11/13 Firefox: 11/13 Firefox for Android: 11/13 Opera: 13/13

API reference documentation


Add event listeners for the various stages of making an HTTP request. The event listener receives detailed information about the request, and can modify or cancel the request.

Chrome: 16/16 Edge: 15/16 Firefox: 15/16 Firefox for Android: 15/16 Opera: 16/16

API reference documentation


Interact with browser windows. You can use this API to get information about open windows and to open, modify, and close windows. You can also listen for window open, close, and activate events.

Chrome: 16/16 Edge: 14/16 Firefox: 16/16 Firefox for Android: 0/16 Opera: 16/16

API reference documentation


Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

Document Tags and Contributors

 Contributors to this page: wbamberg, Sheppy
 Last updated by: wbamberg,