Best ARB File Editors for Flutter: Tools Comparison 2025

Managing ARB (Application Resource Bundle) files is the biggest pain point in Flutter localization. Manual JSON editing leads to syntax errors, missing keys, and inconsistent translations. Here's a comprehensive guide to the best ARB editors available.

What Makes a Good ARB Editor?

Before comparing tools, let's define what matters:

• Syntax validation - Catches JSON errors before they break your build
• Placeholder detection - Ensures {variables} match across languages
• Missing key detection - Highlights untranslated strings
• ICU message support - Handles plurals and gender correctly
• Team collaboration - Multiple translators can work together
• Export quality - Generates valid Flutter-compatible ARB files

Top ARB Editors Compared

1. FlutterLocalisation (Recommended)

Best for: Teams needing AI translation + visual editing

FlutterLocalisation is purpose-built for Flutter developers.

Pros:

• ✅ Visual side-by-side editor
• ✅ AI-powered translation with context
• ✅ Automatic placeholder validation
• ✅ Missing translation detection
• ✅ Real-time collaboration
• ✅ Direct ARB export
• ✅ Flutter-specific features (plurals, select)

Cons:

• Requires account signup
• Free tier has limits

Pricing: Free tier available, Pro from $9/month

Best feature: AI translations that understand Flutter's ICU message format

Upload your ARB → AI translates → Download localized ARB files

2. VS Code with ARB Editor Extension

Best for: Developers who prefer staying in their IDE

The ARB Editor extension for VS Code provides basic ARB editing.

Pros:

• ✅ Free and open source
• ✅ Works inside VS Code
• ✅ Syntax highlighting
• ✅ Basic key navigation
• ✅ No internet required

Cons:

• No translation features
• Limited validation
• Single-file editing only
• No team collaboration

Install:

code --install-extension ArtifactCode.arb-editor

Best feature: Stay in your coding environment

3. Localizely

Best for: Enterprise teams with professional translators

Localizely is a full-featured translation management system.

Pros:

• ✅ Professional TMS features
• ✅ Multiple export formats
• ✅ Translator management
• ✅ Version control integration
• ✅ Translation memory

Cons:

• Complex for small projects
• Expensive for individuals
• Not Flutter-specific
• Generic UI

Pricing: Free tier, paid from $25/month

Best feature: Professional translator workflows

4. POEditor

Best for: Cross-platform projects (iOS + Android + Flutter)

POEditor supports many localization formats including ARB.

Pros:

• ✅ Multi-format support
• ✅ API integrations
• ✅ Machine translation
• ✅ Glossary management
• ✅ QA checks

Cons:

• ARB is not primary format
• Less Flutter-specific features
• UI not optimized for ARB
• Export requires configuration

Pricing: Free up to 1000 strings, paid from $15/month

Best feature: Works across all your platforms

5. Lokalise

Best for: Large enterprises with complex workflows

Lokalise is an enterprise localization platform.

Pros:

• ✅ Powerful automation
• ✅ SDK integrations
• ✅ Advanced workflows
• ✅ In-context editing
• ✅ Screenshot support

Cons:

• Very expensive
• Overkill for small teams
• Complex setup
• Not Flutter-focused

Pricing: From $120/month

Best feature: Enterprise-grade automation

6. Simple JSON Editor (Manual)

Best for: Quick edits, learning ARB format

Any JSON editor works for basic ARB editing.

Recommended editors:

• VS Code with JSON extension
• Sublime Text
• IntelliJ IDEA
• Online: jsoneditoronline.org

Pros:

• ✅ Free
• ✅ No setup
• ✅ Works offline
• ✅ Full control

Cons:

• No ARB-specific features
• Easy to make syntax errors
• No translation help
• No validation
• No collaboration

Best feature: Zero cost, maximum flexibility

Comparison Table

Feature	FlutterLocalisation	VS Code Ext	Localizely	POEditor	Lokalise
Visual Editor	✅	❌	✅	✅	✅
AI Translation	✅	❌	❌	✅	✅
Placeholder Validation	✅	❌	✅	✅	✅
Flutter-Specific	✅	✅	❌	❌	❌
Free Tier	✅	✅	✅	✅	❌
Team Collaboration	✅	❌	✅	✅	✅
Offline Mode	❌	✅	❌	❌	❌
ICU Message Format	✅	❌	✅	✅	✅

How to Choose

Solo Developer, Small Project

Recommendation: FlutterLocalisation free tier or VS Code extension

Start with FlutterLocalisation for AI translations, fall back to VS Code for quick edits.

Small Team (2-5 developers)

Recommendation: FlutterLocalisation Pro

Get AI translation, team collaboration, and Flutter-specific features at reasonable cost.

Medium Team with Translators

Recommendation: Localizely or POEditor

Need professional translator workflows and translation memory.

Enterprise (50+ languages, complex workflows)

Recommendation: Lokalise

Need advanced automation, SDK integration, and enterprise support.

Workflow: Using FlutterLocalisation with VS Code

Here's an optimal workflow combining both:

Step 1: Initial Translation in FlutterLocalisation

1. Create project in FlutterLocalisation
2. Add your English strings
3. Use AI to translate to target languages
4. Review and adjust translations
5. Export ARB files

Step 2: Integration in VS Code

# Copy exported files to your project
cp ~/Downloads/l10n/*.arb lib/l10n/

# Generate Dart code
flutter gen-l10n

Step 3: Quick Edits in VS Code

For minor text changes, edit directly:

// lib/l10n/app_en.arb
{
  "@@locale": "en",
  "buttonText": "Submit Form", // Quick edit here
  "@buttonText": {
    "description": "Submit button label"
  }
}

Step 4: Sync Back to FlutterLocalisation

Upload updated ARB files to keep your translation platform in sync.

ARB Editor Features You Actually Need

1. Missing Translation Detection

Your editor should show which keys are missing in each language:

app_en.arb: 50 keys ✅
app_es.arb: 48 keys ⚠️ (missing: "newFeature", "errorMessage")
app_fr.arb: 50 keys ✅

2. Placeholder Validation

Catch mismatched placeholders before runtime:

English: "Hello, {username}!"
Spanish: "¡Hola, {userName}!" ❌ Wrong: should be {username}

3. ICU Message Preview

See how plurals render with different values:

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

Preview:
  count=0: "No items"
  count=1: "One item"
  count=5: "5 items"

4. Character Limit Warnings

Important for UI fitting:

English: "Submit" (6 chars)
German: "Einreichen" (10 chars) ⚠️ May overflow button

Common ARB Editing Mistakes

1. Invalid JSON Syntax

// ❌ Wrong - trailing comma
{
  "hello": "Hello",
}

// ✅ Correct
{
  "hello": "Hello"
}

2. Missing @ Metadata

// ❌ Works but bad practice
{
  "hello": "Hello"
}

// ✅ Correct - always add metadata
{
  "hello": "Hello",
  "@hello": {
    "description": "Greeting message"
  }
}

3. Incorrect Placeholder Syntax

// ❌ Wrong - using $variable
{
  "greeting": "Hello, $name!"
}

// ✅ Correct - use {variable}
{
  "greeting": "Hello, {name}!",
  "@greeting": {
    "placeholders": {
      "name": {"type": "String"}
    }
  }
}

4. Inconsistent Key Names

// ❌ Inconsistent naming
{
  "helloWorld": "Hello World",
  "goodbye-world": "Goodbye World",
  "THANK_YOU": "Thank You"
}

// ✅ Consistent camelCase
{
  "helloWorld": "Hello World",
  "goodbyeWorld": "Goodbye World",
  "thankYou": "Thank You"
}

Conclusion

The best ARB editor depends on your team size and needs:

• Just starting? → FlutterLocalisation free tier
• Solo developer? → VS Code + FlutterLocalisation for translations
• Small team? → FlutterLocalisation Pro
• Enterprise? → Lokalise or Localizely

Whatever tool you choose, avoid manual JSON editing for anything beyond quick fixes. The time saved and errors prevented are worth the tool investment.

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Ready to stop fighting with ARB files? Try FlutterLocalisation free — the visual ARB editor built specifically for Flutter developers.