Flutter vs React Native Localization: Complete Comparison 2025

Choosing between Flutter and React Native? Localization support should be a key factor. This guide compares i18n capabilities, tooling, and developer experience for both frameworks.

Quick Comparison

Feature	Flutter	React Native
Built-in i18n	Yes (flutter_localizations)	No (needs package)
File format	.arb (JSON-based)	.json or .js
RTL support	Excellent	Good
Pluralization	ICU MessageFormat	Varies by package
Date/Number formatting	intl package	react-native-localize
Hot reload	Yes	Yes
Setup complexity	Medium	Medium-High

Flutter Localization: The Details

Official Solution

Flutter has first-party localization support through flutter_localizations and intl packages.

# pubspec.yaml
dependencies:
  flutter_localizations:
    sdk: flutter
  intl: ^0.18.0

Setup Process

1. Create l10n.yaml

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

2. Create ARB files

{
  "@@locale": "en",
  "hello": "Hello {name}!",
  "@hello": {
    "placeholders": {
      "name": {"type": "String"}
    }
  }
}

3. Use in code

Text(AppLocalizations.of(context)!.hello('World'))

Pros

• Official support - Maintained by Google
• Type-safe - Generated code catches errors at compile time
• ICU MessageFormat - Full pluralization and gender support
• Excellent RTL - Directionality widget handles everything
• Strong tooling - FlutterLocalisation and VS Code extensions

Cons

• Initial setup requires configuration
• ARB format less familiar than JSON
• Code generation step required

React Native Localization: The Details

Popular Solutions

React Native has no official i18n solution. You choose from:

1. react-native-localize + i18n-js (most popular)
2. react-i18next
3. lingui

Setup with i18n-js

1. Install packages

npm install react-native-localize i18n-js

2. Create translation files

// locales/en.js
export default {
  hello: 'Hello {{name}}!',
  items: {
    one: '{{count}} item',
    other: '{{count}} items'
  }
};

3. Configure i18n

import * as RNLocalize from 'react-native-localize';
import i18n from 'i18n-js';

const locales = RNLocalize.getLocales();
i18n.locale = locales[0].languageTag;

4. Use in code

<Text>{i18n.t('hello', { name: 'World' })}</Text>

Pros

• Flexible - Choose your own stack
• Familiar format - Standard JSON files
• Large ecosystem - Many packages available
• JavaScript tooling - Leverage existing i18n libraries

Cons

• No official solution - Must evaluate packages yourself
• Fragmented - Different projects use different approaches
• Less type-safety - Runtime errors more common
• RTL requires work - More manual configuration

Feature-by-Feature Comparison

Pluralization

Flutter (ICU MessageFormat)

{
  "itemCount": "{count, plural, =0{No items} =1{1 item} other{{count} items}}"
}

React Native (i18n-js)

{
  items: {
    zero: 'No items',
    one: '{{count}} item',
    other: '{{count}} items'
  }
}
// i18n.t('items', { count: 5 })

Winner: Flutter - ICU format handles all 6 CLDR plural categories automatically.

Gender/Select Messages

Flutter

{
  "pronoun": "{gender, select, male{He} female{She} other{They}}"
}

React Native - Requires custom implementation or specific packages.

Winner: Flutter - Native ICU select support.

Date/Time Formatting

Flutter

DateFormat.yMMMd('es').format(DateTime.now()) // 9 dic 2025

React Native

new Intl.DateTimeFormat('es', { dateStyle: 'medium' }).format(new Date())

Winner: Tie - Both use platform Intl APIs.

RTL Support

Flutter

Directionality(
  textDirection: TextDirection.rtl,
  child: MyWidget(),
)
// Or automatic with MaterialApp locale

React Native

import { I18nManager } from 'react-native';
I18nManager.forceRTL(true);
// Requires app restart!

Winner: Flutter - Hot-swappable RTL without restart.

Developer Experience

Task	Flutter	React Native
Add new string	Add to ARB, run build	Add to JSON
Missing key detection	Compile error	Runtime error
Rename key	IDE refactor	Find & replace
Translation file sync	Tool support	Manual or custom

Winner: Flutter - Type-safety catches errors earlier.

Tooling Ecosystem

Flutter Tools

Tool	Price	Features
FlutterLocalisation	Free-$99	AI translation, visual editor, Git sync
Localizely	Free-$40	Over-the-air, collaboration
VS Code ARB Editor	Free	Syntax highlighting, validation

React Native Tools

Tool	Price	Features
Lokalise	$120+	Full TMS, OTA updates
Phrase	$25+	Collaboration, API
i18next	Free	Framework integration

Winner: Flutter - More Flutter-specific affordable options.

Migration Complexity

Adding i18n to Existing App

Flutter: Medium

• Configure l10n.yaml
• Create ARB files
• Replace hardcoded strings
• Code generation integrates smoothly

React Native: Medium-High

• Choose and install packages
• Create translation structure
• Replace all text components
• Configure locale detection

Switching Languages at Runtime

Flutter

MaterialApp(
  locale: _userLocale, // Just change state
)

React Native

i18n.locale = newLocale;
// Components need to re-render
// RTL change needs app restart

Winner: Flutter - Simpler runtime switching.

Performance Considerations

Bundle Size

Flutter:

• Translations compiled into app
• Only loaded locales included
• Minimal overhead

React Native:

• JSON files bundled
• All locales typically included
• Can lazy-load with additional setup

Runtime Performance

Both frameworks handle localization with negligible performance impact for typical apps.

Which Should You Choose?

Choose Flutter If:

• You want official, maintained i18n support
• Type-safety is important to you
• You need excellent RTL support
• You prefer visual translation management
• Your team values compile-time error detection

Choose React Native If:

• You have existing JavaScript i18n expertise
• Your team prefers JSON over ARB format
• You need maximum flexibility in tooling choices
• You're already deep in the React ecosystem
• You want to share translations with web React apps

Conclusion

For localization specifically, Flutter has the edge:

Criteria	Winner
Official support	Flutter
Type-safety	Flutter
RTL support	Flutter
Pluralization	Flutter
Tooling cost	Flutter
File format familiarity	React Native
Ecosystem flexibility	React Native

If internationalization is critical to your app's success, Flutter's built-in support and strong tooling (like FlutterLocalisation) make it the more robust choice.

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Building a multilingual Flutter app? Start with FlutterLocalisation - AI-powered translations with native ARB support.