JSON Validator Online

What is a JSON Validator?

A JSON Validator checks whether a piece of text is valid JSON according to theJSON specification. It detects syntax errors such as missing commas, unclosed brackets, trailing commas, unquoted keys, and invalid escape sequences — and reports the exact location of each problem.

JSON (JavaScript Object Notation) has strict syntax rules that must be followed exactly. Unlike JavaScript objects, JSON requires double-quoted keys, does not allow trailing commas, and does not support comments. Even a single misplaced character can cause a parser to reject the entire document. Our JSON Validator uses the browser's native JSON parser to validate your data and provides precise, developer-friendly error messages with exact line numbers and column positions so you can fix issues in seconds.

Common JSON Errors Detected

• Trailing commas — Extra comma after the last item in an object or array
• Single quotes — JSON requires double quotes for strings
• Unquoted keys — Object keys must be enclosed in double quotes
• Missing commas — Forgotten separators between key-value pairs
• Comments — Standard JSON does not allow comments
• Unclosed brackets — Missing ] or }

Auto-Repair Invalid JSON

Our JSON Validator includes an auto-repair feature that can fix many common issues automatically. Click the Repair button to attempt to fix trailing commas, single quotes, unquoted keys, and comments in your JSON data. The repair engine uses pattern-based correction to convert JavaScript-like objects into strict JSON, saving you from tedious manual fixes.

How to Validate JSON

1. Paste your JSON data into the input editor
2. The validator checks your JSON instantly as you type
3. If errors are found, the status bar shows the exact error message with line number
4. Click Repair to auto-fix common issues, or manually correct the error

JSON Validator vs. JSON Formatter

A JSON Validator checks whether your JSON is syntactically correct, while a JSON Formatter restructures valid JSON with proper indentation. JSON Reader Online combines both — validation happens automatically when you paste data, and you can format it with a single click. If your JSON has errors, the validator will flag them before the formatter attempts to beautify the output.

For production workflows, combine the validator with the JSON Minifier to validate and compress your JSON in a single step, or convert validated data to other formats using the JSON to CSV or JSON to YAML converters.