Enter one URL to check whether that page is live.
Enter multiple URLs to check backlinks. The first URL is treated as your target URL, and every URL after it is checked to see if it links to the target.
Backlink checks save one latest record per target/source pair. It does not save endless duplicate history.
Records that have not been checked in 90 days are automatically removed to keep the JSON file small.
This tool can only check public HTML pages. Some sites block automated requests, hide links behind JavaScript, require login, or rate-limit outside checks.
It also blocks private network addresses so the checker cannot be used to scan internal systems.