The Short Version
If you need to know the moment a site goes down, use an uptime monitor like UptimeRobot. If you need to know weeks before a certificate or domain runs out, especially behind Cloudflare, that's what DomainCat is for. Plenty of teams run both, and DomainCat's free plan doesn't ask you to give anything up.
Side by Side
| UptimeRobot | DomainCat | |
|---|---|---|
| Main job | Uptime and response time | Certificates, domains, DNS, email security |
| Certificate it checks behind Cloudflare | The edge cert visitors see (what any hostname check sees) | Edge cert and the origin cert on your server |
| SPF, DMARC, DNS records | Not its focus | Checked per domain |
| Blacklist checks | Not its focus | Spamhaus, SpamCop, Barracuda and more (Pro) |
| Import a Cloudflare account | No | Yes, with a read-only token |
| Ask Claude about your certs (MCP) | No | Yes |
| Price | Free plan; paid from about $12/mo billed yearly | Free for 5 domains; Pro $12/mo, MSP $29/mo |
UptimeRobot details from its public pricing page, November 2026. Check their site for current plans.
The Cloudflare Blind Spot
Any monitor that checks your hostname reaches Cloudflare, not your server, so it reads Cloudflare's edge certificate. Cloudflare renews that one automatically, so it stays green. The certificate on your own server can expire behind it, and the first sign is visitors getting Error 526. DomainCat connects to the origin directly and checks that certificate too. You can see the difference yourself with the free origin certificate checker.
When UptimeRobot Is the Better Fit
If all you need is "tell me when the site is down" with fast check intervals and a public status page, UptimeRobot does that well and DomainCat doesn't try to. DomainCat checks on a schedule (every 6 hours on Free, hourly on MSP) because expiry problems build over weeks, not seconds.
Common Questions
Is DomainCat a replacement for UptimeRobot?
Not for uptime. UptimeRobot tells you when a site is down right now. DomainCat tells you weeks ahead when a certificate, domain or email setting is about to cause an outage. Many teams use both.
Does UptimeRobot check the origin certificate behind Cloudflare?
A hostname check reaches Cloudflare, so it sees Cloudflare's edge certificate, not the one on your server. DomainCat checks the origin certificate directly by connecting to your server's IP.
Is DomainCat free?
Yes for up to 5 domains, with SSL and origin certificate checks every 6 hours and email alerts at 30, 14 and 7 days. Pro is $12 a month for 50 domains and adds domain expiry and blacklist alerts.