The MetaMask browser extension supports new translations added in the form of new locales files added in `app/_locales`.
- [The MDN Guide to Internationalizing Extensions](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Internationalization)
## Adding a new Language
Each supported language is represented by a folder in `app/_locales` whose name is that language's subtag ([look up a language subtag using this tool](https://r12a.github.io/app-subtags/)).
Inside that folder there should be a `messages.json` file that follows the specified format. An easy way to start your translation is to first duplicate `app/_locales/en/messages.json` (the english translation), and then update the `message` key for each in-app message.
That's it! When MetaMask is loaded on a computer with that language set as the system language, they will see your translation instead of the default one.
To automatically see if you are missing any phrases to translate, we have a script you can run (if you know how to use the command line). The script is:
Where `$YOUR_LOCALE` is your [locale string](https://r12a.github.io/app-subtags/), i.e. the name of your language folder.
To verify that your translation works in the app, you will need to [build a local copy](https://github.com/MetaMask/metamask-extension#building-locally) of MetaMask. You will need to change your browser language, your operating system language, and restart your browser (sorry it's so much work!).
