JSON Validator
Check whether a block of JSON is valid and, when it is not, find out where the problem lies. JSON's rules are stricter than they look — one trailing comma invalidates an entire file — and a parser's verdict is considerably faster than reading through by eye.
How to validate JSON
- Paste your JSON.
- Tap Validate, or just keep typing — it checks live.
- Read the result: valid, or exactly what's wrong.
When you'd use this
- Before deploying a config — Catching a syntax error before it breaks something in production.
- API request bodies — Confirming a payload is well-formed before sending it.
- After hand-editing — Manual edits are where trailing commas and unclosed brackets creep in.
- Files from elsewhere — Verifying that JSON produced by another system parses cleanly.
Good to know
- It checks syntax, not meaning — Valid means the structure parses. Whether the fields are the ones your application expects is a different question this cannot answer.
- The strict rules catch people out — Double quotes only, no trailing commas, no comments of any kind, and every key must be quoted.
- Errors point at a position — The parser reports where it gave up, which is normally at or just after the actual mistake.
- Nothing leaves your browser — Validation is local, so a payload containing credentials stays on your machine.
Frequently asked questions
Where does the error message come from?
Directly from the browser's own JSON parser, so it matches what would happen in real code.
Can this also format my JSON?
For formatting or minifying, use the JSON Formatter tool instead.
Why is my JSON invalid when it looks fine?
The three usual culprits are a trailing comma after the final item, single quotes instead of double quotes, and unquoted keys. All three are perfectly legal JavaScript, which is why they end up in JSON so often.
Can JSON contain comments?
No. The format has no comment syntax at all. Some tools accept them as an extension, but strict parsers — this one and most APIs included — will reject them.
Does valid JSON mean my data is correct?
No. It means the syntax parses. A file can be flawless JSON and still carry the wrong field names, missing values or content that makes no sense for your purpose.