Free ARB Editor for Flutter: Validate and Edit Localization Files Online

Tired of hunting for syntax errors in your ARB files? Our Free ARB Editor lets you validate, edit, and fix Flutter localization files instantly — no signup required.

Try It Now

Open Free ARB Editor →

Upload your .arb file or paste content directly. Get instant validation and visual editing.

What Is an ARB File?

ARB (Application Resource Bundle) is Flutter's standard format for localization. It's JSON-based but with specific requirements:

{
  "@@locale": "en",
  "welcomeMessage": "Welcome, {userName}!",
  "@welcomeMessage": {
    "description": "Greeting shown to users",
    "placeholders": {
      "userName": {
        "type": "String",
        "example": "John"
      }
    }
  }
}

Small mistakes break your build. Our editor catches them before flutter gen-l10n does.

Features of Our Free ARB Editor

1. Instant JSON Validation

Upload your file and immediately see:

• ✅ JSON syntax errors (missing commas, quotes, brackets)
• ✅ Invalid ARB structure
• ✅ Encoding issues

2. Placeholder Validation

The editor checks that your placeholders are correctly defined:

// ❌ Error: Placeholder {count} used but not defined
"itemCount": "You have {count} items"

// ✅ Correct: Placeholder properly defined
"itemCount": "You have {count} items",
"@itemCount": {
  "placeholders": {
    "count": {"type": "int"}
  }
}

3. ICU Message Format Support

We validate complex ICU patterns:

Plurals:

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

Gender/Select:

"{gender, select, male{He} female{She} other{They}} liked your post"

4. Visual Entry Editor

Click any translation to:

• Edit the value
• Update the description
• Modify placeholder definitions
• See real-time validation

5. Add New Entries

Create new translation keys with proper metadata:

• Key name
• Translation value
• Description for translators
• Placeholder definitions

6. Sort and Organize

One-click alphabetical sorting keeps your ARB files clean and diff-friendly.

7. Download Fixed Files

Export your validated, edited ARB file ready for Flutter.

Common ARB Errors We Catch

Error: Trailing Comma

// ❌ Invalid JSON
{
  "hello": "Hello",
}

// ✅ Fixed
{
  "hello": "Hello"
}

Error: Unbalanced Braces in ICU

// ❌ Missing closing brace
"{count, plural, =0{None} =1{One} other{{count} items}"

// ✅ Fixed
"{count, plural, =0{None} =1{One} other{{count} items}}"

Error: Undefined Placeholder

// ❌ Uses {name} but no @metadata
{
  "greeting": "Hello, {name}!"
}

// ✅ Fixed - placeholder defined
{
  "greeting": "Hello, {name}!",
  "@greeting": {
    "placeholders": {
      "name": {"type": "String"}
    }
  }
}

Warning: Missing Description

// ⚠️ Warning: No description for translators
{
  "buttonLabel": "Submit"
}

// ✅ Better - description helps translators
{
  "buttonLabel": "Submit",
  "@buttonLabel": {
    "description": "Button to submit the contact form"
  }
}

Error: Wrong Placeholder Syntax

// ❌ Dart syntax, not ARB
"greeting": "Hello, $name!"

// ✅ ARB uses curly braces
"greeting": "Hello, {name}!"

How to Use the Free ARB Editor

Step 1: Open the Editor

Go to flutterlocalisation.com/tools/arb-editor

Step 2: Load Your File

Three options:

• Upload: Click "Upload" and select your .arb file
• Drag & Drop: Drag your file onto the editor
• Paste: Click "Paste" and paste your ARB content
• Try Sample: Click "Load Sample" to see an example

Step 3: Review Validation Results

The editor shows:

• Total keys in your file
• Errors (red) - must fix before build works
• Warnings (yellow) - recommended fixes
• Valid entries (green) - all good

Step 4: Fix Issues

Click any entry to edit:

• Modify the translation value
• Fix placeholder definitions
• Add missing descriptions

Step 5: Download

Click "Download ARB" to save your fixed file.

When to Use This Tool

Quick Validation

Before running flutter gen-l10n, validate your ARB to catch errors early.

Debugging Build Failures

When localization build fails, paste the ARB content to find the exact error.

Creating New Files

Start with our sample and modify it for your app.

Code Reviews

Validate ARB changes in pull requests before merging.

Learning ARB Format

See proper structure with our annotated sample file.

Comparison: Free Editor vs Full Platform

Feature	Free ARB Editor	FlutterLocalisation Platform
Price	Free	Free tier + Pro from $9/mo
Signup Required	No	Yes
Validate ARB	✅	✅
Edit Entries	✅	✅
AI Translation	❌	✅
Multiple Languages	❌	✅
Team Collaboration	❌	✅
Git Integration	❌	✅
Translation Memory	❌	✅

Use the free editor for: Quick validation, one-off edits, learning ARB format.

Use the full platform for: Managing translations across multiple languages, team collaboration, AI-powered translation.

Tips for Clean ARB Files

1. Use Consistent Key Naming

// ✅ Good: camelCase
"welcomeMessage": "...",
"loginButton": "...",
"errorNetworkFailed": "..."

// ❌ Bad: Mixed styles
"welcome_message": "...",
"LOGIN-BUTTON": "...",
"ErrorNetworkFailed": "..."

2. Always Add Descriptions

Translators need context:

"save": "Save",
"@save": {
  "description": "Button to save changes to user profile"
}

3. Define All Placeholders

Even simple strings benefit from type information:

"@greeting": {
  "placeholders": {
    "name": {
      "type": "String",
      "example": "John"
    }
  }
}

4. Use Proper Plural Categories

Different languages need different plural forms:

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

5. Keep Files Sorted

Alphabetically sorted files are easier to:

• Navigate
• Review in diffs
• Merge without conflicts

Our editor has a one-click sort button!

Frequently Asked Questions

Is the ARB editor really free?

Yes, 100% free with no signup required. Use it as much as you need.

Does it work offline?

No, it's a web-based tool. But your files are processed in your browser — we don't store your content.

What file formats are supported?

.arb and .json files. The editor validates ARB-specific features.

Can I edit multiple files at once?

The free editor handles one file at a time. For multi-file management, use the FlutterLocalisation platform.

Does it support all ICU features?

Yes: plurals, select (gender), nested messages, and all placeholder types.

Start Validating Your ARB Files

Stop wasting time debugging localization build errors. Our free ARB editor catches issues instantly.

Open Free ARB Editor →

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