Monibot
Monibot monitors your servers and applications and notifies you if something goes wrong. Monibot monitors the following performance indicators and metrics: CPU/Mem/Disk Usage, Disk/Network IO Activity, Database Size, DB Transaction Latency, Website Uptime, HTTP Response Latency, SSL/TLS Certificates, Cronjob Heartbeats, Number of served requests, HTTP Error Rates, and many more.
Pricing
Their free plan is made for smaller and private projects. For bigger plans you have to contact the Monibot team.
Read more on the pricing page of the service.
Hosting
Monibot is hosted in Germany.