Applanga SDK for Flutter

Table of Contents

Basic Usage

The basic usage of applanga with your flutter project does not need any changes in your code base nor any complex setup. You are able to have all your most actual translations at build time. If you also want your most actual translations at runtime for e.g. already published apps follow the basic usage steps and then go on with Optional Over the Air Updates.

Applanga CLI installation

For the Applanga Command Line Interface (CLI) installation please refer to the official documentation:

There is no need to initialize your project via the Applanga CLI for flutter, applanga_flutter will handle that for you. You can customize your CLI config .applanga.json at anytime. Follow the steps of Localization preparation to get started.

Localization preparation

applanga_flutter works smoothly with the flutter_localizations package. Use the official internationalization guide to add flutter_localizations and intl to your dependencies. Enable the generator in your pubspec.yaml and add the l10n.yaml file and add your first .arb file for your base language. E.g.:

file: lib/l10n/app_en.arb



Add the localizations delegate to your MaterialApp

const MaterialApp(
  localizationsDelegates: AppLocalizations.localizationsDelegates,
  supportedLocales: AppLocalizations.supportedLocales,
  home: MyApp(),

Add your API Token to the bottom of your pubspec.yaml

  access_token: xxxxxxxxxxxxxxxx

You can get your API Token on the on the dashboard from your project settings. The token is needed for pulling and pushing new translations. Read more in the next section.

Pull & Push new translations

To be able to perform a push or pull command you will have to setup Applanga CLI first.

Execute dart run applanga_flutter:pull from your shell and the package will download all new strings from all languages and add them to the corresponding arb files.

Execute dart run applanga_flutter:push from your shell and the package will upload all newly added strings from the arb files to the applanga dashboard.

By default your base language .arb file is the single source of truth. So an pull will get and save all translations for all languages except the base language into corresponding arb files. A push will update only strings from the base language which are not uploaded yet to the dashboard. With this configuration a dart run applanga_flutter:push --force is recommended. All translations for the base language and its meta-data (important for icu strings) are uploaded and updated. You can change that push and pull behavior in your .applanga.json.

Over the Air Updates

Over the air updates are optional and available for android and iOS.

iOS: Be aware to add the supported languages to the info.plist. Find more here.

Add Applanga's settings file

  1. Download the Applanga Settings File for your app from the Applanga Project Overview by clicking the [Prepare Release] button and then clicking [Get Settings File] .
  2. Add the Applanga Settings File to your Android modules resources res/raw directory
  3. Also Add the Applanga Settings File to your iOS modules main target. To do this open the iOS module in Xcode and drag the settings file into the project. Make sure to tick the target you want it applied to.

Generate and replace AppLocalizationsClass with ApplangaLocalizationsClass

Generate the ApplangaLocalizationsClass

dart run applanga_flutter:generate

Add the class to your MaterialApp and replace the old delegate & locales:

`import 'package:applanga_flutter/applanga_flutter.dart';`

const MaterialApp(
  localizationsDelegates: ApplangaLocalizations.localizationsDelegates,
  supportedLocales: ApplangaLocalizations.supportedLocales,
  home: MyApp(),

You can get your translations as usual: AppLocalizations.of(context)!.helloWorld)


It's recommended to place the ApplangaWidget as a top-level widget to your WidgetTree. It will notify all sub widgets if over-the-air translations have changed asynchronously. It is also recommended for a better screenshot experience.

void main() async {
    const ApplangaWidget(child: MyApp()),

Default Languages

By default applanga's OTA strings are pulled lazily at runtime. If the user changes the app language, applanga fetches all new translations for the selected language. This can result in an unexpected visual behavior for the user if there are significant new translation changes coming in with a short delay. If you have e.g. a custom language switcher it can be a good idea to fetch all common languages on app start before a user action to avoid a delay when fetching strings lazily.

Add your default languages to your pubspec.yaml, e.g.:

  update_languages: [en, en_US, es, es_CL]

Default Groups

If you use groups, you can define all default groups which should be downloaded at app start. By default only main will be fetched.

We are following the same pattern as for update_languages:

  update_groups: [main, chapter1, chapter2]

Manual OTA update

ApplangaFlutter is fetching all new translations once on app start for your default languages and default groups. You can also programmatically start a new update and define your languages or groups for it.

// with custom language & groups
ApplangaFlutter.update({languages: ['en_US'], groups: ['main', 'chapter2']);

// default update call using default languages and default groups

Draft Mode

Note: Draft Mode is only available for Android and iOS

Applanga's Draft Mode can be be activated with a multi touch gesture which works out of the box on iOS builds but for Android you need to forward input events to the SDK which can be done in a custom MainActivity like so:

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {

    override fun dispatchTouchEvent(ev: MotionEvent): Boolean {
        com.applanga.applanga_flutter.ApplangaFlutterPlugin.dispatchTouchEvent(ev, this)
        return super.dispatchTouchEvent(ev)

Add the following permission inside the manifest tag in your AndroidManifest:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

To trigger the Draft Mode dialog via code you can call ApplangaFlutter.showDraftModeDialog();

Screenshot Menu

Note: Screenshot Menu is only available for Android and iOS - enable Draft Mode first

Once in draft mode you can show or hide the screenshot menu by swiping down with 2 fingers or via code like this ApplangaFlutter.setScreenShotMenuVisible(bool);

Applanga will detect every string and it's position inside the latest ApplangaScreenshotScope or ApplangaScreenshotScopeMixin. In order to get good and clean screenshots make sure to wrap all your screens or widgets with either ApplangaScreenshotScope widget or add ApplangaScreenshotScopeMixin to your state as shown in the examples below and as shown in the example app from this repository.

Use ApplangaScreenshotScope:

class MyDrawer extends StatelessWidget{
    Widget build(BuildContext context) {
        return ApplangaScreenshotScope(child: Drawer(

Or add ApplangaScreenshotScopeMixin to your screen's state:

class _HomeScreenState extends State<HomeScreen> with ApplangaScreenshotScopeMixin {
    // ...

With this approach we get the translations and string positions for each string. With our reverse text matching we connect each translation to a corresponding string id on the dashboard.

For a even better screenshot experience use ApplangaWidget. With ApplangaWidget on top of your widget tree the SDK will take two screenshots: One with all the string keys instead of translations and one with translations. This improves the string position detection (no more reverse text matching) and enables you the option to debug your screens where a string is placed - even dynamically set strings.

We definitely recommend to use ApplangaWidget and ApplangaScreenshotScope (or ApplangaScreenshotScopeMixin).

Automating screenshot upload

Running flutter integration tests you can capture screenshots as simple as:

await ApplangaFlutter.I.captureScreenshotWithTag("main");

Please read Screenshot Menu to improve string position collection for your screenshot. The example contains an integration test which showcases the usage of the automatic screenshot.

Show ID Mode

Enabling Applanga's show id mode will return translation keys instead of the actual translations. This is good for debugging string positions and it is used to improve the screenshot string detection on the screen.

await ApplangaFlutter.I.setShowIdModeEnabled(true);
// or
await ApplangaFlutter.I.setShowIdModeEnabled(false);

Automatic settings files update

This is automatically enabled after doing a pull request. To do this manually use the following command:

dart run applanga_flutter:update_settingsfiles

To disable the automatic behavior add this to your pubspec.yaml:

  access_token: xxxx
  update_settingsfiles_on_pull: false 

For over-the-air updates the applanga settings file is needed. It contains the most actual translations for all languages from the dashboard. It's good practice to have it updated before an app release. Applanga only fetches new translations. If the settings file is up-to-date the first (automatic) ApplangaFlutter.update will result in a very lightweight get request. If the settings file is an old one -> the fetch request will contain a lot more info.


If your project is a branching project use at least applanga_flutter version 3.0.47 and update your settings files. You can define your default branch in your pubspec.yaml:

  access_token: xxxx
  branch_id: xxxx

You can find your branch id in your project settings on the Applanga dashboard. After changing the branch id in your pubspec.yaml you have to run dart run applanga_flutter:generate to regenerate your applanga config. If you change your default branch, you also have to manually download and update your settings files. If the default branch of your settings file differs from your default branch specified in your pubspec.yaml, applanga_flutter throws an exception.

The default branch is used on app start and for update calls. To be sure branching is working look for the log line: Branching is enabled.

To learn more about branching please have a look here.

Enable custom language fallback

You can configure a custom language fallback for Flutter in your pubspec.yaml. When the SDK needs to translate a key with a specified language, it uses the order as provided. This overrides any other system or default fallbacks only for those languages. Other languages work according to the fallback specified using the custom_language_fallback value (or default if it's not set). The fallback is only overridden for the top-level language, so it's not possible to "nest" the custom fallbacks.

    es-CL: [fr, es-US, de, es]
    de-AT: [es, de-AT, de]

Draft Mode

When enabling the Draft Mode you can switch your branch at runtime - an app restart is required. You also can use our draft overlay to switch your current branch. Every screenshot you take is linked to the current branch.

Production Apps

Already published apps that still use settings files without branching and older SDKs will still work and they will use the default branch defined on the Applanga dashboard.