1. What does this tool do
This free online web service check lets you check if websites or APIs are up—enter URLs (one per line) and see HTTP status codes, response times, and availability. Use it for uptime check, API health check, or website status monitoring and debugging. No sign-up, no proxy; your browser fetches each URL directly so nothing goes through our servers. Ideal for uptime check, API health, connectivity debug, or CORS check.
2. How to use it
Quick start: Paste or type URLs (one per line, max 20), add https:// if missing, click Check, then view the table (URL, status code, response time, status). Green = Up or Reachable, Yellow = Redirect, Red = error or blocked.
- Enter URLs — Paste or type URLs, one per line (or comma-separated). Add
https://if missing. - Click Check — The tool validates URLs, then fetches each one in batches of 5.
- View results — A table shows URL, HTTP status code, response time (ms), and status (Up, Redirect, Client Error, Server Error, Timeout, Reachable, CORS blocked).
- Interpret status — Green = Up (2xx) or Reachable (CORS restricted), Yellow = Redirect (3xx), Red = error or blocked.
3. How it works
URLs are parsed (split by newline or comma), trimmed, and validated. Only http and https are allowed. Each URL is first fetched with fetch() mode: "cors" to get full status. If that fails with a CORS-like error, the tool retries with mode: "no-cors" — if the request succeeds, the site is reported as Reachable (status unknown). Requests run from your browser; CORS applies to the first attempt. A 5-second cooldown prevents rapid re-checks. Maximum 20 URLs per run. All computation runs in your browser. No data is sent to our servers.
4. Use cases & examples
- Uptime check — Verify multiple endpoints are responding.
- API health — Quickly ping several API URLs.
- Connectivity debug — See which URLs respond and which time out.
- CORS check — Identify which sites allow cross-origin requests.
Example
- CORS-friendly URLs (e.g. https://httpbin.org/get) → 200, Up
- https://httpbin.org/status/404 → 404, Client Error
- Site with strict CORS → Reachable (CORS restricted) or CORS blocked
5. Limitations & known constraints
- CORS — Sites that block CORS may show "Reachable" (responded; status unknown) or "CORS blocked". Full status codes require CORS-enabled targets.
- Max 20 URLs — Per check.
- 8 s timeout — Each URL has an 8-second limit.
- 5 s cooldown — Wait 5 seconds before running another check.
- http/https only — Other schemes are rejected.
- Browser limits — Subject to same-origin policy and browser fetch behavior.