Research & Discuss uptime monitoring solutions

[sleidig]

We currently use uptime robot, as it has a free tier for basic monitoring. With more instances we are starting to hit the limit there, however. In the longer run, we should also have a strong grasp on exact uptimes for Service Level Agreements and track availability of the multiple services of each instance.

Are there more industry standard solutions that we can switch to? Open Source and possibly self-hosted (or investing in the OSS project by using their SaaS)? Other considerations?