Extensions

Extensions are software programs, built on web technologies (such as HTML, CSS, and JavaScript) that enable users to customize the Chrome browsing experience.

Welcome
Documentation for Chrome extensions developers.
What's new in Chrome extensions
Recent changes to the Chrome extensions platform, documentation, and policy
Getting started
Step-by-step instructions on how to create a Chrome Extension.
Introducing Manifest V3 #
- Welcome to Manifest V3
  An introduction to Manifest V3
- Extensions platform vision
  Where the extensions platform is headed and why
- Overview of Manifest V3
  A description of the features and changes introduced by Manifest V3.
- Migrating to Manifest V3
  A high-level guide to how you can migrate your Manifest V2 extensions to Manifest V3.
- Manifest V3 migration checklist
  A quick reference on migrating your Chrome Extensions from Manifest V2 to Manifest V3.
- Manifest V2 support timeline
  Details of the Manifest V2 phase-out and end of life.
Overview #
- What are extensions?
  An overview of the purpose of Chrome Extensions and how they're developed.
- What are themes?
  Guidelines on how to create a theme.
- Frequently asked questions
  Frequently asked questions about Chrome Extensions.
- Extensions quality guidelines FAQ
  Frequently asked questions about the single purpose policy.
API Reference
The complete reference to all APIs made available to Chrome Extensions. This includes APIs for the deprecated Chrome Apps platform as well as APIs still in beta and dev.
Samples
Examples of extensions that address various use cases and call appropriate Chrome APIs. Use these to learn how extensions work or as a starting point for building your own extensions.
Develop extensions and themes #
- Extension development overview
  An overview of Chrome Extension capabilities and components.
- Manifest file format
  An overview of the manifest.json properties that you can use in your Chrome Extension.
- Architecture overview
  A high-level explanation of the software architecture of Chrome Extensions.
- Declare permissions
  An overview of the valid values for the permissions property in manifest.json.
- Design the user interface
  UI and design guidelines for Chrome Extensions.
- Debugging extensions
  Step-by-step instructions on how to debug Chrome Extensions.
- Samples
In depth: core concepts #
- Message passing
  How to pass messages between extensions and content scripts.
- Content scripts
  An explanation of content scripts and how to use them in your Chrome Extension.
- Manage events with service workers
  How to respond to browser triggers (events) from a Chrome Extension background script.
- Match patterns
  How host permission and content script pattern matching works, with examples.
- Using promises
  How to use promises when calling extensions APIs
- Cross-origin isolation
  Overview of cross-origin isolation for extensions
In depth: security #
- Cross-origin XMLHttpRequest
  How to implement cross-origin XHR in your Chrome Extension.
- Using eval in Chrome extensions
  How to use eval() in a Chrome Extension.
In depth: more topics #
- Overriding Chrome settings
  How to override Chrome settings from a Chrome Extension.
- Extending DevTools
  How to create a Chrome Extension that adds functionality to Chrome DevTools.
- OAuth2: Authenticate users with Google
  Step-by-step instructions on how to build an extension that accesses a user's Google contacts via the Google People API, the Chrome Identity API, and OAuth2.
- Overriding Chrome pages
  How to override the Chrome bookmark manager, history, and new tab pages from your Chrome Extension.
- Rich notifications API
  How to show notifications to your Chrome Extension users.
Modernize your extensions #
- Migrating from background pages to service workers
  How to migrate your Chrome Extension from background pages to service workers, which is a prerequisite for using Manifest V3.
Best practices #
- Protect user privacy
  Guidelines for ensuring that your Chrome Extension protects user privacy.
- Declare permissions and warn users
  How to implement permissions to protect your users and your Extension.
- Stay secure
  How to keep your Chrome Extension secure.
- Accessibility (a11y)
  How to make your Chrome Extension accessible.
- Localization message formats
  Reference documentation about the format of the messages.json file for Chrome Extensions.
- Give users options
  How to let users customize your Extension.
Distributing your extensions #
- Extension hosting
  How to host your Chrome extension.
- Alternative extension installation methods
  How to install Chrome Extensions via preferences JSON or Windows registry.
- Installing extensions on Linux
  How to package, host, and update crx files from a personal server for Linux users.
- Tutorial: Google analytics
  Step-by-step instructions on how to track usage of your Extension with Google Analytics.
Manifest V2 #
- About Manifest V2
  Documentation for Chrome extensions developers.
- Getting started
  Step-by-step instructions on how to create a Chrome Extension.
- Overview #
- Develop extensions and themes #
- In depth: core concepts #
- In depth: security #
  - Cross-origin XMLHttpRequest
  - Using eval in Chrome extensions
- In depth: more topics #
- Modernize your extensions #
  - Migrate to event-driven background scripts
- Best practices #
- Distributing your extensions #