I run Uptime Kuma on a separate RackNerd instance in Amsterdam. My main box is at HostHatch in Amsterdam. Route via London adds 18ms; route via Paris adds 14ms. I notice before users do maybe 60% of the time.
PING hosthatch.com (203.0.113.4): 56 data bytes
64 bytes from 203.0.113.4: icmp_seq=0 ttl=55 time=14.2 ms
64 bytes from 203.0.113.4: icmp_seq=1 ttl=55 time=14.3 ms
What does everyone else do for sub-$5 monitoring? Self-hosted only. I do not trust SaaS for this price tier.