A document with a trailing comma
{ "a": 1, "b": 2, }Line 1, column 19 — a property name was expected
JSON Validator
Check whether a document is valid JSON and get the line, column and reason when it is not.
Result
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About this tool
Validating JSON answers one question: will a parser accept this document? That is worth isolating from formatting, because when an integration fails you usually want to know whether the payload is even syntactically valid before you look at anything else.
When the answer is no, the useful part is where. This validator reports the line, the column and what the parser expected at that point, along with the offending line so you can see the problem in context.
How to use it
- Paste the document you want to check.
- Read the verdict. Valid documents also report what was parsed — an object with n keys, an array with n entries.
- If it is invalid, jump to the reported line and column. The context block shows the failing line with a caret under the exact position.
- Fix and re-check. Validation runs as you type, so the verdict updates immediately.
Examples
Common problems
- The document looks fine but is reported invalid.
- Check for invisible characters. A byte-order mark or a non-breaking space copied from a web page will break parsing without being visible in the editor.
- NaN or Infinity is rejected.
- JSON has no representation for those values. A producer emitting them is not writing JSON; it needs to send null or a string instead.
- Comments cause an error.
- Standard JSON does not allow comments. Some tools accept JSONC or JSON5, but a strict parser — including this one and most APIs — will not.