3 services carry this tag in their source record. Tags come from the provider, not from us — a tag is a claim about what the service does, not proof that it does it well.
Broken links on a page (up to 40 links checked): Reads one page (robots.txt obeyed) and checks up to 40 of its unique links (internal first) with HEAD then GET: broken links with status or error, restricted (401/403/429/...
HTTP 404 Not Found: what it means (no such resource), what a client should do (check the URL), the class it belongs to, whether it is retryable and idempotency-safe, the defining RFC, and common causes. Precise one-code...
Broken link check: extracts the links on a page and HEAD-requests up to 30 of them (external first), reporting status per link and the list of broken (4xx/5xx/unreachable) ones. Content QA without a crawler. $0.01 per pa...