MetaMask Browser Extension

You can find the latest version of MetaMask on our official website. For help using MetaMask, visit our User Support Site.

For general questions, feature requests, or developer questions, visit our Community Forum.

MetaMask supports Firefox, Google Chrome, and Chromium-based browsers. We recommend using the latest available browser version.

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To learn how to develop MetaMask-compatible applications, visit our Developer Docs.

To learn how to contribute to the MetaMask codebase, visit our Contributor Docs.

To learn how to contribute to the MetaMask Extension project itself, visit our Extension Docs.

GitHub Codespaces quickstart

As an alternative to building on your local machine, there is a new option to get a development environment up and running in less than 5 minutes by using GitHub Codespaces. Please note that there is a Limited Free Monthly Quota, and after that GitHub will start charging you.

Note: You are billed for both time spent running, and for storage used

1. Start by clicking the button above
2. A new browser tab will open with a remote version of Visual Studio Code (this will take a few minutes to load)
3. A "Simple Browser" will open inside the browser with noVNC -- click Connect
   • Optional steps:
     • Click the button at the upper-right of the Simple Browser tab to open the noVNC window in its own tab
     • Open the noVNC sidebar on the left, click the gear icon, change the Scaling Mode to Remote Resizing
4. Wait about 20 extra seconds on the first launch, for the scripts to finish
5. Right-click on the noVNC desktop to launch Chrome or Firefox with MetaMask pre-installed
6. Change some code, then run yarn start to build in dev mode
7. After a minute or two, it will finish building, and you can see your changes in the noVNC desktop

Tips to keep your Codespaces usage lower

• You are billed for both time spent running, and for storage used
• Codespaces pause after 30 minutes of inactivity, and auto-delete after 30 days of inactivity
• You can manage your Codespaces here: https://github.com/codespaces
  • You may want to manually pause them before the 30 minute timeout
  • If you have several idle Codespaces hanging around for several days, you can quickly run out of storage quota. You should delete the ones you do not plan to use anymore, and probably keep only 1 or 2 in the long-term. It's also possible to re-use old Codespaces and switch the branch, instead of creating new ones and deleting the old ones.

Codespaces on a fork

If you are not a MetaMask Internal Developer, or are otherwise developing on a fork, the default Infura key will be on the Free Plan and have very limited requests per second. If you want to use your own Infura key, follow the .metamaskrc and INFURA_PROJECT_ID instructions in the section Building on your local machine.

Building on your local machine

• Install Node.js version 24
  • If you are using nvm (recommended) running nvm use will automatically choose the right node version for you.
• Enable Corepack by executing the command corepack enable within the metamask-extension project. Corepack is a utility included with Node.js by default. It manages Yarn on a per-project basis, using the version specified by the packageManager property in the project's package.json file. Please note that modern releases of Yarn are not intended to be installed globally or via npm.
• Duplicate .metamaskrc.dist within the root and rename it to .metamaskrc by running cp .metamaskrc{.dist,}.
  • Replace the INFURA_PROJECT_ID value with your own personal Infura API Key.
    • If you don't have an Infura account, you can create one for free on the Infura website.
  • If debugging MetaMetrics, you'll need to add a value for SEGMENT_WRITE_KEY Segment write key, see Developing on MetaMask - Segment.
  • If debugging unhandled exceptions, you'll need to add a value for SENTRY_DSN Sentry Dsn, see Developing on MetaMask - Sentry.
  • Optionally, replace the PASSWORD value with your development wallet password to avoid entering it each time you open the app.
  • If developing with remote feature flags, and you want to override the flags in the build process, you can add a .manifest-overrides.json file to the root of the project and set MANIFEST_OVERRIDES=.manifest-overrides.json in .metamaskrc to the path of the file. This file is used to add flags to manifest.json build files for the extension. You can also modify the _flags.remoteFeatureFlags in the built version of in the folder to tweak the flags after the build process (these changes will get overwritten when you build again). An example of this remote feature flag overwrite could be:

This is the beginning of the README. Read the rest at the original. Read the full README ↗