If you don’t mind a web UI, Netdata is great. It collects a bunch of metrics once per second and can retain them for a long period of time. The web UI is pretty good. Their Github readme links to some example servers so you can try it out first. Just click the link to use it without an account (that’s optional).
It’s mainly designed for servers, but there’s no reason you couldn’t run it on a client system. They’re focusing a lot on AI/ML-based anomaly detection as well as their cloud offering at the moment, but you don’t have to use either and can just stick to the open-source agent.




It is encrypted at their end - they say the data is encrypted both in transit and at rest.
However, it’s not end-to-end encrypted, in the usual meaning of the term. E2EE usually means that only the sender and intended recipients of the data can decrypt the it, not the company running the service, their affiliates, or any intermediaries.