I self-host a lot of things. Primarily because it is interesting and gives a lot more flexibility/privacy compared to online alternatives. For example, I run:

• Prometheus + Grafana for monitoring various statistics
• Matrix (/element) to send private notifications to/from my server/phone
• Gitea server including automated build/deployment

Most services are accessible through an NGINX reverse-proxy, usually behind a Authelia security layer.
I have also hosted various game servers, including a custom web-GUI to change settings and start/stop the game server. This was done so less-Linux-inclined friends can manage the game themselves. This web-GUI uses Angular and WebSockets to communicate with a C++ program that runs on the server.
All these services are running in Docker on my Ubuntu server.

Some of my not-so-relevant-but-still-interesting-if-you-want-to-get-to-know-me-as-a-person-hobbies:
Indoor (top-rope and lead) climbing (/occasional bouldering)
Badminton
Gaming/hanging with (international) friends

On pause since COVID:

• SCUBA diving
• Airsoft

And finally pushing the definition of 'hobby'; I used to be a blood donor and am now a (blood)plasma donor.