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JSON Validator

Validate and check JSON syntax online. Paste your JSON to instantly detect syntax errors with line numbers and get a detailed structure analysis.

Online JSON Validator & Syntax Checker

This free JSON validator and lint tool checks your JSON data for syntax errors instantly. Whether you are debugging API responses, validating configuration files, or checking JSON syntax before deployment, this JSON checker identifies issues and provides detailed error messages with position information. Use this JSON lint tool to ensure your data conforms to the JSON specification (RFC 8259).

Common JSON Syntax Errors

Error TypeWrongCorrect
Missing comma{"a": 1 "b": 2}{"a": 1, "b": 2}
Trailing comma{"a": 1, "b": 2,}{"a": 1, "b": 2}
Single quotes{'a': 'hello'}{"a": "hello"}
Unquoted keys{a: 1, b: 2}{"a": 1, "b": 2}
Comments{"a": 1 /* comment */}{"a": 1} (no comments)
NaN / Infinity{"val": NaN}{"val": null} or {"val": 0}

Frequently Asked Questions

How to validate JSON?
To validate JSON, paste your data into the input field and click "Validate". The tool will parse the JSON using the standard JSON.parse() method. If the JSON is valid, you will see a success message with structure details (type, key count, depth). If invalid, you will get a detailed error message showing what went wrong and where in the data the error occurs.
What are the most common JSON errors?
The most common JSON errors include: missing commas between key-value pairs, trailing commas after the last element, using single quotes instead of double quotes, unquoted property keys, including comments (not allowed in JSON), and using JavaScript values like undefined, NaN, or Infinity which are not valid JSON values.
What is the difference between JSON and JavaScript objects?
While JSON syntax is based on JavaScript object notation, there are important differences. JSON requires double quotes for all keys and string values, does not allow trailing commas, does not support comments, does not allow undefined or function values, and does not support single quotes. JavaScript objects are more flexible and allow all of these. JSON is a data interchange format, while JavaScript objects are a programming language construct.

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