JSON Validator
JSON Validator checks your JSON against the strict specification and tells you instantly whether it is valid. When it is not, it surfaces the exact error message along with the line and column so you can jump straight to the problem.
Validation happens entirely in your browser, so even sensitive payloads — tokens, configuration, API responses — never leave your device.
How to use JSON Validator
- 1
Paste your JSON
Drop the JSON you want to check into the input box.
- 2
Read the result
A green banner confirms valid JSON; a red banner shows the parser error with its line and column.
- 3
Fix and re-check
Correct the highlighted issue — the status updates live as you type.
What makes JSON valid?
Strict JSON requires double-quoted keys and strings, no trailing commas, and no comments. Values must be one of: object, array, string, number, true, false or null. A single misplaced comma or a single quote is enough to make the whole document invalid.
This validator uses the same parser the browser uses, so anything it accepts will be accepted by your application's JSON.parse as well.
Common validation errors
The most frequent mistakes are trailing commas after the last item, using single quotes instead of double quotes, unquoted object keys, and missing commas between items. The error message names the unexpected token and its position to help you find it.
For large documents the line and column are especially useful: paste, read the location, and scroll straight to it.
Frequently asked questions
- Does the validator send my JSON anywhere?
- No. Validation runs entirely in your browser, so your data never leaves your device.
- Why does it reject comments and trailing commas?
- Those are not part of the JSON specification. Some parsers allow them as extensions, but strict JSON — and JSON.parse — does not.
- Can it show where the error is?
- Yes. When parsing fails the tool reports the underlying message together with the 1-based line and column of the offending character.
Last updated: