Validate and format JSON data instantly. Check for syntax errors, get detailed error messages, and beautify your JSON with proper indentation for debugging.
JSON (JavaScript Object Notation) is the most widely used data format for APIs and web applications. Validating JSON ensures your data is properly structured before sending it to servers or parsing it in applications. Common JSON errors include missing commas, unclosed brackets, trailing commas, and unquoted keys.
Valid JSON = Proper nesting + Quoted string keys + No trailing commas + Correct data typesA valid JSON document follows strict syntax rules: all keys must be double-quoted strings, string values must be double-quoted, no trailing commas allowed, proper bracket/brace nesting, and supported data types (string, number, boolean, null, object, array).
| Input | Output |
|---|---|
| {"name": "John", "age": 30} | ✓ Valid JSON — Parsed successfully with 2 key-value pairs |
| {"name": "John", "age": 30,} | ✗ Invalid JSON — Trailing comma after last property at line 1, column 25 |
| {name: "John", "age": 30} | ✗ Invalid JSON — Unquoted key "name" at line 1, column 2 |