build codecov

This is an adaptation of i18next standard for Dart with support for Flutter localization techniques. This package is still a work in progress. Mind that this is still a pre-1.0.0 so breaking changes may occur frequently.

  • x Support for variables
  • x Support for namespaces
  • x Support for context
  • x Support for simple plural forms (one or plural)
  • x Support for multiple plural forms (one, few, many, plural, ...)
  • x Plural and context fallbacks
  • x Locale and namespace fallbacks
  • x Get string or object tree
  • x Support for nesting
  • x Flutter's LocalizationsDelegate support
  • x Asset bundle localizations data source (retrieves from pubspec.yaml). See the example for more details.
  • Sprintf support
  • Resource caching
  • Retrieve resource files from server
  • Custom post-processing


Simply declare the package in your pubspec.yaml

  i18next: ^0.5.0

To use it with flutter's LocalizationsDelegate you first create I18NextLocalizationDelegate and register it in your WidgetsApp (MaterialApp or CupertinoApp).

  locales: widget.locales,
  // this data source is from where the delegate will retrieve the localizations from (namespaces Map)
  dataSource: ...,
  // optional extra options can be added here
  options: I18NextOptions(...),

Then to access and use it, simply call

Widget build(BuildContext context) {
  // It finds the i18next instance on the widgets tree via `Localizations.of`

But if you want to handle it yourself, then simply instantiate it:

  // This store is from where i18next will attempt to retrieve the localizations from.
  resourceStore: ...,
  // Optional extra options can be added here
  options: I18NextOptions(...)


For the simple and straightforward usages:

  "key": "Hello World!",
  "nested": {
    "key": "My nested key"
i18next.t('key'); // 'Hello World!'
i18next.t('nested.key'); // 'My nested key'

// unmapped keys usually return themselves (when graceful fallback fails)
i18next.t('unspecifiedKey'); // 'unspecifiedKey'
  "key": "Hello {{name}}!",
  "grouped_key": "Hello {{grouped.name}}"
i18next.t('key', arguments: {'name': 'World'}); // 'Hello World!'
i18next.t('grouped_key', arguments: {'grouped': {'name': 'Grouped World'}}); // 'Hello Grouped World!'
  "nesting1": "1 $t(nesting2)",
  "nesting2": "2 $t(nesting3)",
  "nesting3": "3"
i18next.t('nesting1'); // "1 2 3"
  "key": "item",
  "key_plural": "items",
  "keyWithCount": "{{count}} item",
  "keyWithCount_plural": "{{count}} items"
i18next.t('key', count: 0); // 'items'
i18next.t('key', count: 1); // 'item'
i18next.t('key', count: 5); // 'items'
i18next.t('keyWithCount', count: 0); // '0 items'
i18next.t('keyWithCount', count: 1); // '1 item'
i18next.t('keyWithCount', count: 5); // '5 items'

There are also ways of dealing with locales with multiple plural: zero, one, few, many, others (key identifier) (Unsupported)

  • Contexts like gender, are marked via underscores
    "genderMessage": "They",
    "genderMessage_male": "Him",
    "genderMessage_female": "Her"
i18next.t('genderMessage'); // 'They'
i18next.t('genderMessage', context: 'male'); // 'Him'
i18next.t('genderMessage', context: 'female'); // 'Her'

And can be used with plurals

  "friend": "A friend",
  "friend_plural": "{{count}} friends",
  "friend_male": "A boyfriend",
  "friend_female": "A girlfriend",
  "friend_male_plural": "{{count}} boyfriends",
  "friend_female_plural": "{{count}} girlfriends"
i18next.t('friend'); // 'A friend'
i18next.t('friend', count: 1); // 'A friend'
i18next.t('friend', count: 100); // '100 friends'

i18next.t('friend', context: 'male', count: 1); // 'A boyfriend'
i18next.t('friend', context: 'female', count: 1); // 'A girlfriend'
i18next.t('friend', context: 'male', count: 100); // '100 boyfriends'
i18next.t('friend', context: 'female', count: 100); // '100 girlfriends'
  "key1": "{{text, uppercase}} just uppercased",
  "key2": "The current date is {{now, datetime(format:dd/MM/yyyy)}}",
  "key3": "Right now we are in {{now, datetime(format:MMM), uppercase}}."
i18next.t('key1', arguments: { 'text': 'my text' }); // 'MY TEXT just uppercased'
i18next.t('key2', arguments: { 'now': DateTime.now() }); // 'The current date is 21/01/2020'
i18next.t('key3', arguments: { 'now': DateTime.now() }); // 'Right now we are in JAN.'

There are other usages and possibilities as well, this is just an example of what is defined by this format.

  • Namespaces: A namespace can be thought of as logical groupings of different sets of translations. In a given namespace you could have a set of languages, each with their own set of keys. They can also be understood as separate files. For example:

    • common.json: Things that are reused everywhere, eg. Button labels 'save', 'cancel'
    • validation.json: All validation texts
    • glossary.json: Words we want to be reused consistently inside texts
// common.json
  "myKey": "This key is in common"

// feature.json
  "myKey": "This key is in my feature"
i18next.t('common:myKey'); // 'This key is in common'
i18next.t('feature:myKey'); // 'This key is in my feature'
  • Context/plural fallback mechanism:
  "friend": "A friend",
  "friend_female": "A girlfriend"
i18next.t('friend'); // 'A friend'

i18next.t('friend', count: 1); // 'A friend'
// It fallbacks to `friend` since `friend_plural` is not present
i18next.t('friend', count: 2); // 'A friend'

i18next.t('friend', context: 'female'); // 'A girlfriend'
// It fallbacks to `friend` since `friend_male` is not present
i18next.t('friend', context: 'male'); // 'A friend'

There is a way to also set the default namespace or a order of namespaces so a key knows where to start looking for the translation.