Lit Localization Service

A Flutter package to create localizations using JSON files.


English Localization German Localization
'Hello Word' in English Localization 'Hello Word' in German Localization

How it works

The JSON file is fetched on the localization delegate. Its content will then be extracted into a local Map and made accessible using the BuildContext. The localized strings can then be read by calling LitLocalizations.of(context).getLocalizedValue("your_key_you_specified_on_the_json_file") on the build method.

Reading essential values like texts from local storage will require a status check of the current fetch process on startup. This will increase the loading time of your application. It's used best when already depending on a persistent storage solution where loading processes on startup are required anyway.

How to use


  • Provide a JSON file containing all localized strings in a predefined structure (Vide infra).
  • Include the JSON file asset on your pubspec.yaml file of your app.
  - assets/json/
  • Include lit_localization_service as git dependency on your pubspec.yaml file of your app:

or as a pub dependency:

  • Set the localizationsDelegates property value of your MaterialApp by initializing the LitLocalizationServiceDelegate. Provide your JSON file's location.
  localizationsDelegates: [
    // The LitLocalizationServiceDelegate will be passed here.
      // Set your asset url
      jsonAssetURL: 'assets/json/localized_strings.json',
      // Set all language code whose localization are available on the json file
      supportedLanguages: ['en', 'de'],
      // State whether to output logs.
      debug: true,
  • Create a FutureBuilder to call the initLocalizations method in order to montitor the parsing state and conditionally returning either your screen containing your localized strings or a fallback/loading screen
class ParsingStateBuilder extends StatelessWidget {
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: LitLocalizationController()
      builder: (context, localizatonsInitalization) {
        return localizatonsInitalization.connectionState ==
            ? LoadingScreen()
            : MyHomeScreen();
  • Call your localized strings by accessing the BuildContext once the parsing has been finished.
  • This should display the string 'Hello' extracted from your JSON file as a Flutter Text widget.

JSON file structure

The JSON file should contain a list of objects, whose keys can be arbitrary. Each of these objects will in turn have a list of key-value pairs, representing the language and the localized string "languageCode": "Localized String".

  "hello": {
    "en": "Hello",
    "de": "Hallo"
  "world": {
    "en": "World",
    "de": "Welt"

Getting Started with Flutter

For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.


The example folder contains an example app demonstrating the most basic implementation using a local JSON asset file.


The source code of this repository is distributed under the BSD 3-Clause license as specified in the LICENSE file.