Free Online Tool

JSON Validator & Formatter

Validate, format, and beautify your JSON data instantly. Our JSON validator checks for syntax errors, provides detailed error messages, and formats your JSON with proper indentation — making it easy to read and debug.

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Formatting Options

Waiting for JSON input…

Paste your JSON here

Characters: 0 | Lines: 0 | Size: 0 bytes

Output

Characters: 0 | Lines: 0 | Size: 0 bytes

Instant Validation

Real-time JSON validation with detailed error messages showing exactly what's wrong and where.

Format & Minify

Beautify JSON for readability or minify it to reduce file size for production use.

Error Detection

Get helpful tips about common JSON mistakes and how to fix them quickly.

How to Validate & Format JSON

Quick Steps:

  1. 1Paste or type your JSON data in the left panel
  2. 2The tool will automatically validate your JSON
  3. 3If valid, see the formatted JSON on the right
  4. 4If invalid, see detailed error messages and fix them
  5. 5Copy or download the validated JSON

Features:

  • •
    Real-time Validation: Instantly see if your JSON is valid or has errors.
  • •
    Beautify Mode: Format JSON with proper indentation (2, 4, or 8 spaces).
  • •
    Minify Mode: Compress JSON to smallest size by removing whitespace.
  • •
    Error Messages: Clear error descriptions with tips on how to fix them.
  • •
    Statistics: View character count, line count, and file size.

Valid vs Invalid JSON Examples

Invalid JSON (Common Mistakes)

{ name: "John", // Key not quoted 'age': 30, // Single quotes "city": "NYC", // Correct "active": true, // Correct "items": [1, 2, 3,] // Trailing comma }

Valid JSON (Properly Formatted)

{ "name": "John", "age": 30, "city": "NYC", "active": true, "items": [1, 2, 3] }

Common Use Cases

🔍 API Development

Validate API request/response payloads during development

📝 Configuration

Check JSON config files for syntax errors before deployment

🐛 Debugging

Find and fix JSON parsing errors in your applications

📚 Learning

Understand JSON structure and syntax rules with examples

JSON Syntax Rules

✅ Must Follow:

✓Data is in name/value pairs

✓Data is separated by commas

✓Curly braces hold objects {}

✓Square brackets hold arrays []

✓Keys must be strings in double quotes

✓String values must use double quotes

❌ Common Errors:

✗Using single quotes instead of double quotes

✗Trailing commas after last element

✗Unquoted keys or property names

✗Missing commas between elements

✗Comments (JSON doesn't support comments)

✗Undefined or function values

Pro Tips

1

Copy from APIs

Paste JSON responses directly from API calls to validate them

2

Use Minify for Production

Minified JSON reduces bandwidth and improves load times

3

Read Error Messages

Error messages tell you exactly what's wrong and where

4

Test Before Using

Always validate JSON before using it in your application