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/creationix/nvm#installation) (recommended) running `nvm use` will automatically choose the right node version for you.
- 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).
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.
1.**required**`yarn build:test` to create a test build.
2. run tests, targetting the browser:
* 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.
*`yarn.lock`:
* Run `yarn setup` again after your changes to ensure `yarn.lock` has been properly updated.
* 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.
* The production LavaMoat policy files (`lavamoat/browserify/*/policy.json`), which are re-generated using `yarn lavamoat:background:auto`. Add `--help` for usage.
- [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)
