Auto Translator

A command-line tool that simplifies translation of an ARB template file to selected languages. This package is designed to work seamlessly with the flutter_localizations and intl packages, Flutter's preferred internationalization approach.


  • Seamless integration with flutter_localizations and intl packages.
  • Works with Google Cloud Translate & DeepL Translate.
  • Minimal quota usage.
  • Works with simple & complex ARB strings, conditions, and variables.
  • Uses placeholder examples for more accurate translations involving proper nouns and other unique cases.
  • Specify translator service and/or source language for individual target languages.

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Getting Started

1. Setup Translation Service(s)

Auto Translator supports Google Cloud Translate and DeepL out of the box. You may specify either one as your primary service in the l10n.yaml config file. If neither is provided, the default (Google) is used. You may also specify different translators on a per-language basis, as seen in Preferred Services.

If you are configuring only one service, you can save the API key in a file in the project root directory called translator_key or as a json map in translator_keys. If configuring both services, you must use the json map approach.

:warning: DO NOT publish your key file to Github or similar VCS.

You can also specify an alternate key file path.

Google Cloud Translate

If you do not have a Google Cloud Project with the Cloud Translation API enabled, follow the guide here.

DeepL Translate

If you do not have DeepL API access, follow DeepL's guide to creating an account and obtaining API access here

2. Add auto_translator to your project

Add auto_translator under dev_dependencies in pubspec.yaml

  auto_translator: ^2.3.2

3. Setup the config files

auto_translator uses the same config file as the intl package, Flutter's recommended package for internationalizing your app, as explained here.

If you have not already created the l10n.yaml file, do so now.

arb-dir: lib/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart

  #Defaults to Google Translate.
  service: Google

    - es-ES
    - fr
    - ja

The first three parameters are used by intl as well as auto_translator. The translator section is specific to auto_translator.

The targets parameter is required and tells auto_translator which languages to translate the template file to. Available languages can be found here.

You can also configure preferred source templates for any given target language.

Regional Designations

You can use 2-letter language codes and regional designations (en-US, en-GB, es-Es, etc.).

4. Run the package

Once configured, run the package from the command line.

flutter pub get
dart run auto_translator

All translations will be placed in the defined location and be compatible with flutter_localizations and intl.

Additional Usage

Placeholder Examples

Some translations are more accurate when using an example in place of a generic placeholder variable name. auto_translator now passes a placeholder's example if provided to ensure better quality translations.

"viewingArtwork": "Now viewing {artworkTitle}.",
  "@viewingArtwork": {
      "placeholders": {
          "artworkTitle": {
              "type": "String",
              "example": "Mona Lisa"

Force Translation

To prevent unecessary Google Cloud Translate quota usage, messages that already exist in a target ARB file are not retranslated. You can force a translation by adding the force parameter to translator options in a message's metadata in the template file.

"title": "New Title",
"@title": {
  "description": "...",
  "translator": {
    "force": true

Ignore ARB String

You can also tell the translator to ignore a particular message with the ignore tag.

"doNotTranslate": "DO NOT TRANSLATE THIS STRING!!!",
"@doNotTranslate": {
  "description": "...",
  "translator": {
    "ignore": true

Preferred Templates

Sometimes, you may wish to specify a language that translates more accurately to a target than the language used in the template-arb-file. For that, you can provide a prefer-lang-templates map to specify a preferred source language to use as a template for any target language.

  # use es-ES template for fr translation ja for ko
  # all other translations will use [template-arb-file]
    fr: es
    ko: ja

Preferred Services

As one service may outperform the other in a given language you may wish to specify a service an a per-language basis. This can be done by providing a prefer-service map in the config file.

  # use DeepL for tr and uk
  # all other translations will use the primary service
  # (presumably Google in this case)
    # capitilization does not matter for service name
      - tr
      - uk

Each API key must be provided in the key file (service name capitalization does not matter).

  "deepL": "DEEP_L_API_KEY"

Alternate config file

By default, the config file is named l10n.yaml and is located in the project's root directory. You can pass in an alternate file path when running on the command line using the --config-file option.

Alternate key file

By default, auto_translator looks for keys in the project root at translator_keys or translator_key. You may specify a different location in the config file.

  key_file: path/to/key/file