A single misplaced comma can break an entire API response or config file. This validator parses your JSON in the browser and tells you immediately whether it's valid — and if not, exactly where it fails.
What 'valid JSON' means
Valid JSON follows a strict grammar: double-quoted keys and strings, no trailing commas, no comments, and correctly balanced braces and brackets. Anything else — however readable — isn't JSON and will be rejected by strict parsers.
Reading the error
When parsing fails, the position in the message is your fastest clue. Trailing commas and single quotes are the usual suspects; work outward from the reported location to find the mismatched bracket or stray character.
Frequently asked questions
Paste it above — if it parses, you'll see it cleanly formatted; if not, the error message points to the exact position and reason it failed.
The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments, and stray or missing brackets. Strict JSON allows none of these.
No. Validation happens entirely in your browser — the JSON you paste never leaves your device.