That JSON parse error — on this line, at this column, and here is what the server sent back.
Paste a URL or a blob of JSON. Linetrap parses it and, when it fails, points at the exact line and column and says what was expected there in plain language — not “unexpected token at position 4471.”
One paste. One answer.
Paste a URL or JSON blob
Enter an API endpoint that returns JSON, or paste raw JSON text directly. For URLs, Linetrap fetches what the server actually sends — no assumptions, no cache.
Linetrap pinpoints the error
If the JSON is invalid, you get the exact line and column where parsing failed, plus a plain-language explanation — not a V8 stack trace. Valid JSON gets a green confirmation and structural overview.
See what the server really sent
For URLs, Linetrap reports the raw response: the actual content-type, the status code, whether the body is JSON at all, and whether it is an error object wearing a 200 status — a surprising share of “my API is broken” turns out to be an HTML error page with a 200 status and a JSON content-type.
What you get
Pinpoint line & column
Not “position 4471.” Linetrap converts the raw byte offset to a human-readable line:column pair and says what the parser expected there.
Raw response inspection
For fetched URLs, see the actual content-type, status code, response body, and whether the response was truncated — because the bug is sometimes in the server, not your code.
Client-side privacy
Pasted JSON text never leaves your browser. It is parsed right here, locally. Only URL-based requests travel through the server, and nothing is logged or stored.
No account required
Linetrap is entirely stateless. There is no sign-up, no saved history, no tracking. Open the page, paste, get your answer, close the tab.
What Linetrap cannot do
Cannot reach hosts behind Cloudflare. Linetrap runs on Cloudflare Workers, and the platform will not open a connection back to its own network. If your target is fronted by Cloudflare, Linetrap reports it as unreachable — not as closed or firewalled. This affects a large share of the public web.
No email, alerts, or scheduled re-checks. There is no email sender or notification system. Linetrap is a one-shot diagnostic tool — it does not watch endpoints or send digests.
No crawling or link following. Linetrap fetches exactly the URL you type and nothing else. It does not follow redirects, crawl linked resources, or retry failed endpoints.
Ready to see where that JSON broke?
No sign-up, no account, no tracking. Just paste and get your answer.
Open Linetrap