Plex/Ombi/Calibre and a bunch of related services. The devs who built these things run Discord servers where all day people pop in for guidance and troubleshooting. I had multiple devs spend 10+ hours over the last month walking me through reverse proxies, DNS/SSL certs, setting up all these services on my site, configuring and theming everything... it's just incredible to me.

I had to donate money to each of their groups, because these people are so committed to building and sharing free and open-source software and providing support to novices... it just gives me hope for humanity. They have a certain set of skills and just found a way to provide a service that many people will benefit from. And they share it freely and willingly! It made me happy. Especially so once my site was completed and I was able to sit back and enjoy/take pride in what I'd cobbled together.