JSON Validator.
Check whether your JSON is valid and pinpoint syntax errors by exact line and column. Fast, free, and 100% private — it runs in your browser.
No signup · No uploads · Free forever
Result
// Paste JSON and press “Validate JSON”.Validate JSON online — find errors instantly
A JSON validator tells you whether a document is well-formed JSON and, when it is not, exactly where it breaks. Paste your JSON above and press Validate JSON: the tool parses it locally and reports either “Valid JSON” with key, array, and depth counts, or the precise line and column of the first syntax error.
Common JSON errors this catches
- Trailing commas after the last item in an object or array.
- Single quotes or unquoted keys — JSON requires double quotes.
- Mismatched brackets
and[ ]. - Comments, which standard JSON does not permit.
- Smart quotes and stray characters pasted from documents.
Validate privately, then keep working
Validation runs entirely client-side, so it is safe for sensitive data. Once your JSON checks out, format it for readability, minify it for production, or explore it as a tree. New to the format? Read common JSON errors and how to fix them.
FAQ
JSON validation, answered.
How do I validate JSON online? +
Paste your JSON into the validator above and press Validate JSON. The tool parses it in your browser and tells you immediately whether it is valid. If it is not, you get the exact line and column of the first syntax error so you can fix it fast.
What makes JSON invalid? +
The most common causes are trailing commas, missing or mismatched brackets and braces, single quotes instead of double quotes, unquoted keys, and comments (which standard JSON does not allow). The validator points to the precise location of the first problem it finds.
Does the validator check against a JSON Schema? +
This tool checks JSON syntax — whether the document is well-formed and parseable. It does not yet validate against a JSON Schema (type and shape rules). For structural checks, format the JSON and inspect it with the JSON viewer.
Is my JSON sent anywhere when I validate it? +
No. Validation happens entirely in your browser. Your JSON never leaves your device, so it is safe to validate configuration, tokens, or private API responses.
Why does my JSON say invalid when it looks fine? +
Look closely at the reported line and column. Common hidden culprits are a trailing comma after the last array or object item, smart/curly quotes pasted from a document, or a stray non-printing character. The error message and position pinpoint exactly where parsing failed.