JSON Validator
Validate JSON syntax with detailed error locations, line numbers, and auto-formatting.
Detailed Error Location
Pinpoints the exact line and column of syntax errors with visual indicators and context preview.
Auto Format
Automatically format valid JSON with proper indentation. Makes nested structures easy to read and debug.
Client-Side Processing
All validation runs in your browser. No data is sent to any server, ensuring complete privacy.
How to Use the JSON Validator
- 1. Paste your JSON string into the Input JSON panel on the left.
- 2. Click Validate to check for syntax errors. The result shows valid/invalid status with error details.
- 3. If invalid, the error message shows the exact line and column number with a context preview.
- 4. Click Format to auto-format valid JSON with proper indentation.
- 5. Use the Line Numbers / Formatted toggle to switch the output view.
Frequently Asked Questions
What does a JSON validator check?
A JSON validator checks for syntax errors including mismatched braces/brackets, missing commas, trailing commas, unquoted keys, invalid escape sequences, and incorrect data types. It reports the exact line and column where the error occurs.
What is the difference between JSON validation and JSON formatting?
JSON validation checks whether the JSON is syntactically correct. JSON formatting (or pretty-printing) adds indentation and line breaks to make valid JSON more readable. This tool does both: it validates first, then optionally formats the output.
Why does my JSON have a trailing comma error?
The JSON specification (RFC 8259) does not allow trailing commas after the last element in an array or object. While JavaScript allows them, JSON parsers will reject them. Remove the comma after the last item to fix this error.
Is my data safe when using this JSON validator?
Yes. All validation and formatting happens entirely in your browser using JavaScript. No data is sent to any server. Your JSON never leaves your device.