Resolve the site's IP and check it against 15 major DNSBL spam/abuse blacklists. Use before sending mail from, or trusting, a host. WARN = listed on 1–2 lists; DOWN = listed on 3 or more.

Resolve a DNS record (A by default) for the host and return the values. Use to confirm a domain resolves and to detect missing or misconfigured records.

Look up the domain's registration expiry via WHOIS and report the expiry date and days remaining. Use to catch domains about to lapse before they drop and take DNS/email/site down with them.

Fetch a URL and report whether it is reachable, the HTTP status code, and the response time in milliseconds. A fast liveness/uptime probe — run it before relying on a site or as a cheap health signal.

Load the full page and measure time-to-first-byte, total load time, and downloaded size (capped at 5 MB). Use to gauge front-end performance before crawling, embedding, or depending on a page.

Run HTTP + SSL + DNS + domain-expiry in one call and return a combined health snapshot. The single pre-flight check to run before crawling, deploying to, or depending on a site — cheaper and one round-trip instead of four.

Inspect the site's TLS/SSL certificate: whether it is currently valid and how many days remain until it expires. Use to catch soon-to-expire or already-expired certificates before they break HTTPS for visitors.