JSON Validator & Syntax Linter
Drop in some JSON and this tells you immediately whether it's valid, pointing to the exact line and column of any error in plain language. It parses safely — never with eval — so your data stays private while you chase down a malformed response or config file.
- 100% free
- Private & safe
- Runs in your browser
Read our complete guide: Understanding JSON: How to Validate, Format, and Minify Payloads
Why use JSON Validator?
JSON Validator is a quick, no-nonsense developer utility that runs entirely client-side, so your code and data never leave your machine.
- Runs instantly in your browser — nothing to install, nothing uploaded.
- Completely free, with no account, no watermarks and no usage limits.
- JSON (RFC 8259)
- Paste your JSON into the input box.
- Works on any device — desktop, tablet and phone — and is fully keyboard accessible.
How to use JSON Validator
- Paste your JSON into the input box.
- Click Validate (or load the example to see the format).
- A green panel confirms valid JSON; otherwise you get a clear message with the line and column.
- Fix the issue and re-validate.
Examples
- Confirming an API response is well-formed JSON.
- Finding the trailing comma that breaks a config file.
Supported formats & limits
- JSON (RFC 8259)
Limitations
- Comments and trailing commas are not valid JSON and are reported as errors.
- Extremely large inputs are guarded for performance.
Frequently asked questions
Does it fix my JSON?
No, it validates and locates errors. Use JSON Formatter to prettify valid JSON.
Is my JSON uploaded?
No — validation happens entirely in your browser.
Why is my trailing comma an error?
Standard JSON does not allow trailing commas or comments, unlike JavaScript objects.
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