Browser Extensions
Extensions, or add-ons, can modify and enhance the capability of a browser. Extensions for Firefox are built using the WebExtensions API cross-browser technology.
The technology for extensions in Firefox is, to a large extent, compatible with the extension API supported by Chromium-based browsers (such as Google Chrome, Microsoft Edge, Opera, Vivaldi). In most cases, extensions written for Chromium-based browsers run in Firefox with just a few changes.
Key resources
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Guides
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Whether you're just beginning or looking for more advanced advice, learn about how extensions work and use the WebExtensions API from our extensive range of tutorials and guides.
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References
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Get comprehensive details about the methods, properties, types, and events of the WebExtensions APIs and full details about the manifest keys.
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Firefox workflow
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Discover how to build and publish extensions for Firefox: get the lowdown on developer tools, publication and distribution, and porting on Extension Workshop.
User interface
Discover all the user interface components you can use in your extensions, with coding examples and tips.
Firefox workflow
When you are ready to create your extension for Firefox or port your Chrome extension, head over to Extension Workshop. It has details on:
JavaScript APIs
Get comprehensive details about the methods, properties, types, and events for all the JavaScript APIs. There is also detailed information about the compatibility of each API with the major browsers. Most reference pages also include coding examples and links to the extension examples that use the API.
Manifest keys
Get full details about the manifest keys, including all their properties and settings. There's also detailed information on the compatibility of each key with the major browsers.