JSON Validator
Paste JSON to check whether it is syntactically valid. Invalid input reports the exact line and column of the first error.
Frequently asked questions
What makes JSON invalid?
The most common offenders: trailing commas, single quotes instead of double quotes, unquoted keys, comments, and NaN/undefined values. Strict JSON allows none of these — this validator points at the first one it hits.
Where exactly is my JSON error?
When validation fails, this tool parses the browser engine's error message and converts the character position into a line and column, so you can jump straight to the problem even in large files.
Is my JSON uploaded to a server?
No. Validation runs locally with your browser's built-in JSON parser. Nothing is transmitted — you can confirm this by watching the network tab while you validate.