You're looking for a dead man's switch. https://deadmanssnitch.com is a good hosted service or Uptime Kuma (https://github.com/louislam/uptime-kuma) can be configured to do the same thing. - Source: Hacker News / about 1 month ago

Uptime Kuma can also monitor certificate expiration; you can also enable it to show you how many days are left until it expires. https://github.com/louislam/uptime-kuma. - Source: Hacker News / 4 months ago

- Web terminal & live logs I'm trying it as an alternative to Portainer and I'm loving it. It seems to fit perfectly in my flow. Code and more info: https://github.com/louislam/uptime-kuma (Not affiliated, just a happy user). - Source: Hacker News / 5 months ago

Uptime Kuma is a self-hosted monitoring service that you can use to keep track of the heath of your applications, websites, and APIs. You can configure it to watch services with different types of health checks and set up email notifications for when there are problems. Uptime Kuma also lets you design custom status pages that you can use to share public information about your service health statuses and to... - Source: dev.to / 8 months ago

It's for people who owns a log of servers/computers at home and need to monitor its uptime. For safety reason, it's impossible to expose the system to the public internet, we can only use the "push" strategy to report the up status. This tool is just for this purpose: request an URL at some interval repeatedly. Recommended to use this with uptime-kuma ( - Source: Hacker News / 9 months ago

Also, there are websites that give you estimates of how much another site earns from ads (e.g. siteworthtraffic.com). Source: almost 2 years ago