What SiteIsOkBot is, what it requests, and how to allowlist or block it
What it is
SiteIsOkBot is the scanner for Site is OK?, a website infrastructure health checker. It is not a crawler: it never follows links or discovers content on its own. It only fetches a domain when a user explicitly asks us to check that domain.
Every request identifies itself honestly — we never spoof a browser or another bot:
SiteIsOkBot/1.0 (+https://siteisok.com/bot)
What it requests
Standard checks — a handful of requests: the homepage over HTTP and HTTPS, redirect hops, and a few well-known files (e.g. robots.txt). DNS, TLS certificate, and email-security checks use their own protocols and send no HTTP beyond that.
Intrusive checks — only when a registered user explicitly runs one for a domain they have verified control of (token published on the host or in DNS). These send a bounded set of read-only GET/HEAD requests to well-known sensitive paths (e.g. /.env, /.git/HEAD) and may open SMTP connections to the domain's mail servers. No logins, no exploitation, no fuzzing, no writes.
How it behaves
Paced — requests are sent a few at a time (at most 5 in flight) with a delay between them, never as one large burst.
Bounded — each scan has a hard per-scan request budget (~80 for a standard check, ~160 when intrusive probing runs); it cannot run away. Redirect chains are capped at 3 hops. The exact count is shown on each scan result — requests sent to the domain itself, broken down by kind, plus any lookups sent to resolver/registry/CA services (DNS, RDAP, OCSP) rather than the target.
Polite under throttle — a 429 with a Retry-After header is honored with a single retry after the requested wait.
Stops when refused — if a host repeatedly returns the same refusal (403/429/…) or stops answering, the scan aborts early instead of continuing to probe. A domain that once blocked us is re-scanned on an exponential backoff (1 h → 24 h), not on every schedule tick.
Scanner IP addresses
Requests originate from these addresses:
91.121.36.27
2001:41d0:8:8ae9::10
Allowlist or opt out
To allow the scanner through a WAF or bot-protection layer, allowlist the User-Agent above or the listed IPs. To stop being scanned entirely, block either of those — our checks will report your site as "refused/filtered" rather than down — or contact support@siteisok.com and we will exclude your domain.