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Free JSON Validator

Validate JSON syntax instantly. Find missing commas, brackets, quotes, and syntax errors. Perfect for debugging JSON data and API responses.

Last Updated: 15 Jan 2026

Paste JSON Content

What is JSON Validation?

JSON validation is the process of checking JSON (JavaScript Object Notation) data against the JSON specification (RFC 7159) to ensure it's syntactically correct and can be parsed by JSON parsers. JSON is a strict format—even minor syntax errors like a missing comma or an extra trailing comma can cause parsing to fail.

JSON validators parse your JSON data and identify syntax errors, providing clear error messages that help you quickly locate and fix issues. This is essential for debugging API responses, configuration files, data files, and any application that works with JSON data.

Why Use Our Free JSON Validator?

Instant Validation

Validate JSON instantly as you type or paste. No delays, no server requests. All validation happens in your browser for maximum speed and privacy.

Clear Error Messages

Get precise error messages indicating the exact location and type of syntax error. Quickly identify missing commas, unclosed brackets, or invalid quotes.

RFC 7159 Compliant

Validates against the official JSON specification (RFC 7159), ensuring your JSON is compatible with all standard JSON parsers and libraries.

Common Use Cases for JSON Validation

API Development

API Response Debugging
Validate JSON responses from REST APIs, GraphQL, or webhooks to ensure they're properly formatted before processing.
Request Validation
Validate JSON request payloads before sending to APIs to catch syntax errors early and prevent integration issues.
Configuration Files
Validate JSON configuration files (package.json, tsconfig.json, etc.) to ensure they're syntactically correct before use.

Data Processing

Data Import/Export
Validate JSON data files before importing into databases or applications to prevent data processing errors.
Error Prevention
Catch JSON syntax errors before they cause application crashes or data corruption. Validate early in your development workflow.
Learning JSON
Use the validator to learn JSON syntax by checking your JSON as you write it. Error messages help you understand JSON rules.

Common JSON Syntax Errors

Missing Commas

Commas must separate all items in objects and arrays. Missing commas cause parsing errors.

{ "name": "John" "age": 30 }

Unclosed Brackets

All opening brackets {[ must have matching closing brackets ]}. Unclosed brackets cause parsing failures.

{ "name": "John"

Invalid Quotes

JSON strings must use double quotes. Single quotes or unquoted keys cause syntax errors.

{ 'name': 'John' }

Trailing Commas

Trailing commas after the last item in objects or arrays are not allowed in standard JSON (though some parsers allow them).

{ "name": "John", }

Frequently Asked Questions

What does JSON validation check?

JSON validation checks your JSON data against RFC 7159 standards. It identifies syntax errors like missing commas, unclosed brackets or braces, invalid quotes, trailing commas, and other formatting issues that prevent JSON from being parsed correctly.

Will validation fix JSON errors?

Our validator identifies and reports errors with clear messages indicating the problem location. While it doesn't automatically fix errors, the error messages help you quickly locate and fix issues manually.

Can I validate large JSON files?

Yes, our JSON validator can handle large JSON files efficiently. However, extremely large files (10MB+) may take longer to validate. For best performance, validate files under 1MB.

Is my JSON data secure when using this tool?

Yes, all JSON validation happens entirely in your browser using JavaScript. Your data never leaves your device, ensuring complete privacy and security.

Does validation check data types?

Our validator checks JSON syntax (structure, brackets, commas, quotes) but doesn't validate data types or values. For schema validation (checking data structure and types), use JSON Schema validators.

Can I validate JSON5 or JSONC?

Our validator works with standard JSON (RFC 7159). JSON5 (with comments and trailing commas) and JSONC (JSON with Comments) are not standard JSON and may not validate correctly.

What if my JSON is minified?

Minified JSON (without whitespace) validates just as well as formatted JSON. Our validator works with both. Use our JSON formatter to beautify minified JSON for readability.

Does it validate nested JSON?

Yes, our validator handles deeply nested JSON structures, arrays within objects, objects within arrays, and any valid JSON hierarchy regardless of nesting depth.