Browser Extensions

Extensions can extend and modify the capability of a browser. Extensions for Firefox are built using the WebExtensions API, a cross-browser system for developing extensions. To a large extent the system is compatible with the extension API supported by Google Chrome and Opera and the W3C Draft Community Group.

Extensions written for these browsers will in most cases run in Firefox or Microsoft Edge with just a few changes. The API is also fully compatible with multiprocess Firefox.

If you have ideas or questions, or need help migrating a legacy add-on to use WebExtensions APIs, you can reach us on the dev-addons mailing list or #webextensions on IRC.

Getting started

Concepts

User interface

How to

Porting

Firefox workflow

Reference

JavaScript APIs

Manifest keys

Related Topics
  1. Browser extensions
  2. Getting started
    1. What are extensions?
    2. Your first extension
    3. Your second extension
    4. Anatomy of an extension
    5. Example extensions
    6. What next?
  3. Concepts
    1. Using the JavaScript APIs
    2. Content scripts
    3. Match patterns
    4. Working with files
    5. Internationalization
    6. Security best practices
    7. Content Security Policy
    8. Native messaging
  4. User interface
    1. User Interface
    2. Accessibility guidelines
    3. Toolbar button
    4. Address bar button
    5. Sidebars
    6. Context menu items
    7. Options page
    8. Extension pages
    9. Notifications
    10. Address bar suggestions
    11. Developer tools panels
  5. How to
    1. Intercept HTTP requests
    2. Modify a web page
    3. Insert external content
    4. Add a button to the toolbar
    5. Implement a settings page
    6. Work with the Tabs API
    7. Work with the Bookmarks API
    8. Work with the Cookies API
    9. Work with contextual identities
    10. Build a cross-browser extension
    11. Onboard, upboard, and offboard users
  6. Porting
    1. Firefox differentiators
    2. Porting a Google Chrome extension
    3. Porting a legacy Firefox extension
    4. Comparison with the Add-on SDK
    5. Comparison with XUL/XPCOM extensions
    6. Differences between API implementations
    7. Chrome incompatibilities
    8. Differences between desktop and Android
  7. Firefox workflow
    1. Developer tools
    2. Choose a Firefox version
    3. User Experience
    4. Prompt users for data and privacy consents
    5. Temporary Installation in Firefox
    6. Debugging
    7. Testing persistent and restart features
    8. Test permission requests
    9. Developing for Firefox for Android
    10. Getting started with web-ext
    11. web-ext command reference
    12. Extensions and the Add-on ID
    13. Request the right permissions
    14. Best practices for updating your extension
  8. JavaScript APIs
    1. Browser support for JavaScript APIs
    2. alarms
    3. bookmarks
    4. browserAction
    5. browserSettings
    6. browsingData
    7. captivePortal
    8. clipboard
    9. commands
    10. contentScripts
    11. contextualIdentities
    12. cookies
    13. devtools.inspectedWindow
    14. devtools.network
    15. devtools.panels
    16. dns
    17. downloads
    18. events
    19. extension
    20. extensionTypes
    21. find
    22. history
    23. i18n
    24. identity
    25. idle
    26. management
    27. menus
    28. notifications
    29. omnibox
    30. pageAction
    31. permissions
    32. pkcs11
    33. privacy
    34. proxy
    35. runtime
    36. search
    37. sessions
    38. sidebarAction
    39. storage
    40. tabs
    41. theme
    42. topSites
    43. types
    44. userScripts
    45. webNavigation
    46. webRequest
    47. windows
  9. Manifest keys
    1. author
    2. background
    3. browser_action
    4. browser_specific_settings
    5. chrome_settings_overrides
    6. chrome_url_overrides
    7. commands
    8. content_scripts
    9. content_security_policy
    10. default_locale
    11. description
    12. developer
    13. devtools_page
    14. dictionaries
    15. externally_connectable
    16. homepage_url
    17. icons
    18. incognito
    19. manifest_version
    20. name
    21. offline_enabled
    22. omnibox
    23. optional_permissions
    24. options_page
    25. options_ui
    26. page_action
    27. permissions
    28. protocol_handlers
    29. short_name
    30. sidebar_action
    31. theme
    32. theme_experiment
    33. user_scripts
    34. version
    35. version_name
    36. web_accessible_resources
  10. Distribution Options
  11. Themes
  12. Browser themes
    1. Browser theme concepts
    2. Using the AMO theme generator
  13. Publishing and Distribution
  14. Publishing add-ons
    1. Developer accounts
    2. Signing and distribution overview
    3. Package your extension
    4. Submit an add-on
    5. Source code submission
    6. Resources for publishers
    7. Creating an appealing listing
    8. Make money from browser extensions
    9. Promoting your extension or theme
    10. Add-on policies
    11. Developer agreement
    12. Featured add-ons
    13. Retiring your extension
  15. Distributing add-ons
    1. For sideloading
    2. For desktop apps
    3. For an enterprise
  16. Community and Support
  17. Channels
    1. Add-ons blog
    2. Add-on forums
    3. Stack Overflow
    4. Contact us