JSON Validator
Check whether JSON is valid and find the exact problem when it isn't. Errors are shown with the line, column and a pointer to the character; common mistakes — trailing commas, single quotes, comments, unquoted keys, Python True/None — can be fixed automatically in one click.
Paste JSON and it's validated as you type against the JSON standard (RFC 8259). Valid JSON is shown formatted with key, object, array and depth counts; invalid JSON shows the error location. If the problem is a common hand-editing mistake, an auto-fix produces valid JSON you can apply or copy.
Zero Server Uploads
Files process in local RAM
Instant WASM Speed
No waiting queues or lags
Unlimited Batching
Convert files without limits
Suggest a Feature or Improvement for JSON Validator
Need custom options, higher limits, or extra format support? Let our engineering team know!
How to use JSON Validator
- 1Paste your JSON.
- 2Read the result — valid, or the exact error location.
- 3Apply the auto-fix if offered.
- 4Copy the formatted JSON.
The most common JSON errors
A trailing comma after the last item, single quotes instead of double quotes, unquoted keys, comments (JSON has none), missing commas between items, and values like undefined, NaN or Python's True/None. JSON copied from JavaScript objects or config files often has several of these.
Smart quotes from word processors and invisible characters (byte-order marks) are also common culprits.
Formatting and exploring
For tree views, minifying and more formatting options, use the JSON Formatter. Check YAML configs with the YAML Validator and API payloads with the API Response Formatter.
Frequently Asked Questions
Does it validate against a JSON Schema?
Not yet — it checks that the JSON is well-formed. Schema validation is on our list.
Is my code or data uploaded?
No. Everything runs in your browser; nothing you paste is sent to a server or stored.