What this JSON validator checks
A JSON validator (or JSON syntax checker, or JSON lint tool) verifies that a document follows the JSON grammar defined in RFC 8259: double- quoted strings, comma-separated members, matched braces and brackets, and no extras like comments or trailing commas. This tool runs your input through a strict parser — the same one browsers and Node.js use — so if it passes here, it will parse anywhere.
When validation fails, the raw parser message can be cryptic (“Unexpected token } in JSON at position 47”). This validator translates that character position into a line and column number, so you can jump straight to the offending spot in your editor instead of counting characters.
How to validate JSON online
- Paste the JSON document into the box above.
- Click Validate JSON.
- Read the verdict: a summary of the document if valid, or the error and its location if not.
- Fix the reported issue and validate again until the document passes.
Validation vs. formatting
Validation answers one question: will this parse? If you also want to make the document readable, run it through the JSON Formatter after it validates — formatting requires a successful parse first, so the two tools naturally work together when debugging API responses, webhook payloads and configuration files.