- Each supported language is represented by a folder in `app/_locales` whose name is that language's subtag (example: `app/_locales/es/`). (look up a language subtag using the [r12a "Find" tool](https://r12a.github.io/app-subtags/) or this [wikipedia list](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes)).
- Inside that folder there should be a `messages.json`.
- An easy way to start your translation is to first **make a copy** of `app/_locales/en/messages.json` (the English translation), and then **translate the `message` key** for each in-app message.
- **The `description` key** is just to add context for what the translation is about, it **does not need to be translated**.
- Add the language to the [locales index](https://github.com/MetaMask/metamask-extension/blob/master/app/_locales/index.json) `app/_locales/index.json`
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:
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!).