A surgical diagnostic instrument for JSON parsing failures. Paste a JSON blob or enter a URL. Jsonprobe points at the exact line and column where parsing broke and says what was expected there — not just "unexpected token at position 4471". For URL fetches it reports what the server actually sent: the content-type, whether the body is JSON at all, and whether it is a JSON error object dressed as a success.
Paste any JSON blob. The parse happens entirely in your browser — the text never leaves your device. When it fails, you get the exact line, column, position, and a plain-language description of the expected token. No data is sent to any server.
Enter a URL and the server fetches it on your behalf. The report shows HTTP status, content-type, media type, body size, final URL after redirects, and whether the response body is valid JSON. When the response is malformed JSON, the same line/column diagnostic applies.
A surprising share of "my API is broken" is an HTML error page with a 200 status and a JSON content-type. Jsonprobe flags non-2xx responses and marks every derived verdict as unreliable, because an error page is not a reading of the site.
Hosts that are themselves behind Cloudflare cannot be reached from this server. The tool says so plainly next to the input rather than reporting them as closed or unreachable for an unknown reason.
No account. No sign-up. No data stored.