The JSON validator checks whether a document is well-formed against RFC 8259 and pinpoints the first syntax error by line and column. Instead of a vague "invalid JSON" from your code, you get the exact spot and reason so you can fix it in seconds.
Validation runs in your browser with no upload, so you can safely check a production API response, a secret-bearing config or a customer record. It is free, instant and requires no account.
It is for anyone debugging a broken payload: a missing comma from a hand edit, an unquoted key, a stray trailing comma, or a truncated response. The tool marks the problem inline and tells you what the parser expected.
By default the validator enforces the JSON standard exactly: keys and strings must use double quotes, no comments are allowed, and numbers follow the spec's grammar. This matches how servers, databases and standard parsers will read your data.
Real-world files sometimes carry a trailing comma before a closing bracket or brace. Turn on the trailing-comma option to accept that relaxed style so you can validate config-like input without rewriting it first.
When parsing fails, the validator reports the line and column of the first offending character plus a short snippet of the surrounding text, so you can jump straight to the problem instead of scanning the whole document.
A valid JSON document is a single value — an object, array, string, number, boolean or null — with balanced brackets, quoted keys and no leftover characters after it. The validator confirms all of this in one pass.
Comments, trailing commas, single-quoted or unquoted keys, and non-standard number formats like hexadecimal or leading-plus. These are common in JavaScript objects but are not valid JSON.
Only if you are validating a relaxed, config-style file that intentionally uses them. For data that a standard parser will consume, keep strict mode on so you catch commas that would otherwise fail server-side.
The error is usually just before the flagged position: a missing comma or an unclosed string on the previous line makes the parser fail at the next token. Check the character right before the marker.
Yes. Validation is entirely client-side. Your input never leaves the browser tab, so tokens and production data stay private.
It means the syntax is well-formed. It does not check that the values match a schema or your business rules — for that, use the JSON Schema generator and validator.