You can find the latest version of MetaMask on [our official website](https://metamask.io/). For help using MetaMask, visit our [User Support Site](https://metamask.zendesk.com/hc/en-us).
To learn how to contribute to the MetaMask project itself, visit our [Internal Docs](https://github.com/MetaMask/metamask-extension/tree/develop/docs).
- If you are using [nvm](https://github.com/nvm-sh/nvm#installing-and-updating) (recommended) running `nvm use` will automatically choose the right node version for you.
- ONLY follow the steps in the "Install Corepack" and "Updating the global Yarn version" sections
- DO NOT take any of the steps in the "Initializing your project", "Updating to the latest versions" or "Installing the latest build fresh from master" sections. These steps could result in your repo being reset or installing the wrong yarn version, which can break your build.
- Replace the `INFURA_PROJECT_ID` value with your own personal [Infura Project ID](https://infura.io/docs).
- If debugging MetaMetrics, you'll need to add a value for `SEGMENT_WRITE_KEY` [Segment write key](https://segment.com/docs/connections/find-writekey/), see [Developing on MetaMask - Segment](./development/README.md#segment).
- If debugging unhandled exceptions, you'll need to add a value for `SENTRY_DSN` [Sentry Dsn](https://docs.sentry.io/product/sentry-basics/dsn-explainer/), see [Developing on MetaMask - Sentry](./development/README.md#sentry).
- Optionally, replace the `PASSWORD` value with your development wallet password to avoid entering it each time you open the app.
To get quick feedback from our shared code quality fitness functions before committing the code, you can install our git hooks with Husky.
`$ yarn githooks:install`
You can read more about them in our [testing documentation](./docs/testing.md#fitness-functions-measuring-progress-in-code-quality-and-preventing-regressions-using-custom-git-hooks).
To start the [React DevTools](https://github.com/facebook/react-devtools), run `yarn devtools:react` with a development build installed in a browser. This will open in a separate window; no browser extension is required.
To start the [Redux DevTools Extension](https://github.com/reduxjs/redux-devtools/tree/main/extension):
- Install the package `remotedev-server` globally (e.g. `yarn global add remotedev-server`)
- Install the Redux Devtools extension.
- Open the Redux DevTools extension and check the "Use custom (local) server" checkbox in the Remote DevTools Settings, using the default server configuration (host `localhost`, port `8000`, secure connection checkbox unchecked).
Then run the command `yarn devtools:redux` with a development build installed in a browser. This will enable you to use the Redux DevTools extension to inspect MetaMask.
To create a development build and run both of these tools simultaneously, run `yarn start:dev`.
#### Test Dapp
[This test site](https://metamask.github.io/test-dapp/) can be used to execute different user flows.
You can run the linter by itself with `yarn lint`, and you can automatically fix some lint problems with `yarn lint:fix`. You can also run these two commands just on your local changes to save time with `yarn lint:changed` and `yarn lint:changed:fix` respectively.
- Firefox e2e tests can be run with `yarn test:e2e:firefox`.
- Chrome e2e tests can be run with `yarn test:e2e:chrome`. The `chromedriver` package major version must match the major version of your local Chrome installation. If they don't match, update whichever is behind before running Chrome e2e tests.
Whenever you change dependencies (adding, removing, or updating, either in `package.json` or `yarn.lock`), there are various files that must be kept up-to-date.
- Run `yarn` again after your changes to ensure `yarn.lock` has been properly updated.
- Run `yarn lint:lockfile:dedupe:fix` to remove duplicate dependencies from the lockfile.
- The `allow-scripts` configuration in `package.json`
- Run `yarn allow-scripts auto` to update the `allow-scripts` configuration automatically. This config determines whether the package's install/postinstall scripts are allowed to run. Review each new package to determine whether the install script needs to run or not, testing if necessary.
- Unfortunately, `yarn allow-scripts auto` will behave inconsistently on different platforms. macOS and Windows users may see extraneous changes relating to optional dependencies.
- If you are a MetaMask team member and your PR is on a repository branch, you can use the bot command `@metamaskbot update-policies` to ask the MetaMask bot to automatically update the policies for you.
- If your PR is from a fork, you can ask a MetaMask team member to help with updating the policy files.
- Manual update instructions: The _tl;dr_ is to run `yarn lavamoat:auto` to update these files, but there can be devils in the details:
- There are two sets of LavaMoat policy files:
- The production LavaMoat policy files (`lavamoat/browserify/*/policy.json`), which are re-generated using `yarn lavamoat:background:auto`. Add `--help` for usage.
- These should be regenerated whenever the production dependencies for the background change.
- The build system LavaMoat policy file (`lavamoat/build-system/policy.json`), which is re-generated using `yarn lavamoat:build:auto`.
- This should be regenerated whenever the dependencies used by the build system itself change.
- Whenever you regenerate a policy file, review the changes to determine whether the access granted to each package seems appropriate.
- Unfortunately, `yarn lavamoat:auto` will behave inconsistently on different platforms.
macOS and Windows users may see extraneous changes relating to optional dependencies.
- If you keep getting policy failures even after regenerating the policy files, try regenerating the policies after a clean install by doing:
- [Extend MetaMask's features w/ MetaMask Snaps.](https://docs.metamask.io/guide/snaps.html)
- [Prompt your users to add and switch to a new network.](https://medium.com/metamask/connect-users-to-layer-2-networks-with-the-metamask-custom-networks-api-d0873fac51e5)
- [Change the logo that appears when your dapp connects to MetaMask.](https://docs.metamask.io/guide/defining-your-icon.html)
