Add a custom localization to ThingsBoard Mobile Application

Add a new language to the mobile app build or improve an existing translation.

The ThingsBoard mobile app includes the following languages by default:

• English
• Arabic
• Chinese (Taiwan)
• Chinese (Simplified)

The app reads localized strings from .arb files in lib/l10n. Each .arb file represents one locale — for example, intl_en.arb for English. Keys stay the same across all languages; only the values change per locale.

For full details on Flutter’s internationalization system, see the official Internationalizing Flutter apps guide.

1. Open the localization folder.

   Go to your project’s lib/l10n directory. You’ll see files like:

   intl_ar.arb
   intl_en.arb
   ...

   

2. Create a language file.

   Add a new .arb file named using the format intl_<languageCode>.arb. For example:

   • intl_es.arb — Spanish
   • intl_fr.arb — French
   • intl_de.arb — German

   For a region-specific variant, use BCP-47 style — for example, intl_pt_BR.arb.

3. Add translations.

   Copy the contents of intl_en.arb into the new file. Translate only the values (the text on the right of each key). Do not change the keys.

   {
     "appTitle": "Your App Title Translation",
     "login": "Your Login Translation",
     "password": "Your Password Translation"
   }

4. Generate localization files.

   App version 1.7.0 and later — install the Flutter Intl extension, which automatically tracks localization changes and regenerates files:

   • VS Code — Flutter Intl extension
   • IntelliJ / Android Studio — Flutter Intl plugin

   Without the extension — add intl_utils to dev dependencies and run the generator manually:

   flutter pub add -d intl_utils

   dart run intl_utils:generate

   Run the generate command after each change to your .arb files.

   App version before 1.7.0 — run:

   flutter gen-l10n

• Change your device or simulator language to the target locale and relaunch the app.
• For right-to-left languages like Arabic, verify layout mirroring and text direction.
• Check that pluralization, placeholders, and date/number formatting look correct.

Community contributions to improve localization are welcome. To contribute:

• Open a pull request to the <a href="https://github.com/thingsboard/flutter_thingsboard_app" target="_blank" rel="noopener noreferrer">flutter_thingsboard_app</a> repository with your new or updated .arb files.
• Submit an improvement request with the .arb files attached.