Help Centre
Everything you need to use Linetrap — getting started, common questions, known limitations, and how to get help.
Getting started
Open the app
Go to /app. You will see two tabs: Paste JSON text and Fetch a URL. Choose the one that fits your situation.
Paste JSON text (or enter a URL)
If you have a blob of JSON you want to validate, paste it into the text area and click Parse locally. The parsing happens entirely in your browser — nothing leaves your machine.
If you are debugging an API endpoint, switch to the URL tab, paste the URL, and click Fetch and parse. Linetrap will fetch the endpoint, show the raw response, and run the same parse analysis.
Read the result
Valid JSON gets a green confirmation with a structural overview. Invalid JSON shows the exact line and column of the error, a plain-language explanation of what went wrong, and a highlighted snippet of the problem area. For URLs, you also get the status code, content-type, and whether the body was truncated.
No account needed
Linetrap is completely stateless — no sign-up, no saved history, no tracking. Open the page, paste, get your answer, and close the tab. That is the whole flow.
Frequently asked questions
Linetrap says “Line 1, column X” — what does that actually mean?
The JavaScript JSON.parse() error message normally gives you a raw byte position (“at position 4471”). Linetrap converts that position into a human-readable line and column number, then explains what the parser was expecting at that spot. For example, “Found an unexpected identifier — JSON property names must be in double quotes.” If you see a line/column from Linetrap, that is exactly where the problem is in the text you pasted or the response body we fetched.
Why does Linetrap show a different result than my browser's dev tools?
When you fetch a URL, Linetrap reports what the server actually sent. A surprising number of APIs return an HTML error page (with a 200 status and a JSON content-type header) when something goes wrong server-side. Your browser's fetch may silently fail or show a network error, while Linetrap shows you the bytes that came back. If Linetrap says the response is valid JSON but the structure is wrong, the problem is likely in your code rather than the wire format. If Linetrap says the response is not JSON at all, the server is the problem.
Does Linetrap store or log my data?
No. JSON text pasted into the app is parsed locally in your browser and never sent to any server. For URL requests, the fetch goes through a Cloudflare Worker that returns the response and immediately discards it. No logs, no analytics, no tracking, no cookies, no accounts. Everything is stateless by design. See the Privacy Policy for details.
Can I use Linetrap to monitor an API endpoint?
No. Linetrap is a one-shot diagnostic tool. It fetches exactly the URL you type, runs the analysis, and stops. There is no email sender, no notification system, no scheduled re-checks, and no way to watch an endpoint over time. If you need monitoring, you will need to use a dedicated uptime or API monitoring service.
What is the response body limit? What happens if my API returns more than that?
The Free plan has a 50 KB response body limit and a 15-second fetch timeout. If the response is larger than 50 KB, Linetrap truncates the body and marks it as truncated — you will still see the metadata and the first 50 KB of content. A Pro plan with a 500 KB limit and 30-second timeout is planned for late 2026. See Pricing for details.
Linetrap says the host is unreachable — but I can reach it from my browser. What is going on?
Linetrap runs on Cloudflare Workers. Cloudflare Workers cannot connect back to any host that is also behind Cloudflare — the platform blocks connections to its own network. If the host you are testing is fronted by Cloudflare (a very large share of the public web), Linetrap reports it as unreachable. This is not a network problem — it is a platform limitation. See Known limitations below for more.
Known limitations
Cloudflare-hosted targets are unreachable. Linetrap runs on Cloudflare Workers, and the platform will not open a connection back to its own network. If the endpoint you are testing is behind Cloudflare, Linetrap reports it as unreachable. This affects a large share of public APIs and is not something the tool itself can work around.
No crawling or link following. Linetrap fetches exactly the URL you type and stops. It does not follow redirects, crawl linked resources, or retry a different endpoint. If the server responds with a 3xx status, Linetrap reports that status and shows whatever body (if any) was returned — it never follows the redirect.
No email, alerts, or scheduled re-checks. There is no email sender or notification system connected to this fleet. Linetrap is a one-shot diagnostic tool — it does not watch endpoints, send digests, or notify you of changes. If you need persistent monitoring, you will need a dedicated service.
Free plan body limit: 50 KB. Responses larger than 50 KB are truncated. A Pro plan (planned for late 2026) will increase this to 500 KB. The Free cap covers single-object and moderate-size payloads well, but large API responses or Base64-heavy payloads will hit the limit.
No API key or programmatic access yet. Linetrap is a web-only tool. There is no public API, no authentication, and no way to call the parser from a script. Programmatic access is planned under the Pro plan for late 2026.
No payment processor connected. The Pro plan, checkout form, and billing terms describe a product that will be available once payment processing is operational. Until then, only the Free plan is available. No real payments are accepted today.
Contact & support
Getting help
Most questions are answered above in the FAQ. If you have encountered a bug or have a question that is not covered here, please read the known limitations first — some issues are platform-level constraints that the tool cannot change.
Contact by email
Email-based support is not yet available. This is a known gap — a contact inbox for support queries has been identified as a requirement and will be added when the business infrastructure is set up.
Until then, the tool is entirely self-service. If you believe you have found a genuine bug, please document the steps to reproduce it — the relevant information will be collected when a contact route exists.
Email support — plannedReport a bug or suggest a feature
There is no bug tracker or feature request system set up yet. If you have a suggestion, please note it down — the process for collecting user feedback will be established when the business contact details are finalised.
Feedback system — planned