Uptime monitoring on your own instance: check whether your services respond and see how your servers are doing — without a cap on the number of checks.
Open source alternatives
UptimeRobot Checkmate
start.me
FlameA browser start page with everything you open every day: services, bookmarks and a search box. On your own instance, without an account with a provider.
Pingdom Checkmate
Check whether your website responds and how fast, with a history and an alert when something goes down. On your own instance, with no price per check.
Statuspage Checkmate
A public status page that tells your users whether everything is up, fed by your own checks. On your own instance.
StatusCake Checkmate
Uptime checks for websites and servers, with response times, history and a status page. On your own instance, without tiers on the number and interval of checks.
Better Stack Checkmate
For the uptime part: check whether your services respond, report outages, show a status page. Plus, if you like, the load on your servers. On your own instance.
Datadog Beszel
For a handful of servers, less will do: CPU, memory, disk and network over time, containers per machine and alerts on thresholds. On your own instance, with no price per host.