First I think it's best to get this out of the way:
DO NOT use this on a production environment or anywhere security is a big concern. I wrote this application with the sole purpose of running it on an isolated network with some media servers on it.
I know this may sound like the code is terrible, or at the very least, a big budge. And that's because that's exactly what it is. I wrote this as a weekend project (although I've been thinking about making something similar for quite some time now) and I only now I thought about sharing with other people.
As of today (12/01/2020), it's missing quite a lot of features that I should have probably implemented by now (access logs, the ability to add/remove/edit users from the interface itself, comments...) but I might get around adding them later this week.
I made this because I have some computers at home that I constantly (and by that I mean at least once every day), but that I cannot leave turned on because, A, they're incredibly loud at night, and B, I don't feel like throwing my savings out the window paying electricity bills. Since none of them are connected to the internet, and they really shouldn't be at any time, I figure it'd be nice if I didn't need to go down stairs to my basement every time I needed to turn them on. Which lead us to where I am now.
I made some Flask applications in the past (a REST API and a couple of websites), so doing this wasn't much of an issue. I did wanted to make my own implementation of the Wake On Lan standard, but honestly, WOL works pretty well and is brain-dead easy to set up, so I ended up using it. I'm well aware that there are probably dozens of different solutions to this exact same issue I had, all of which probably work a heck of a lot better than this bare-bones hack of mine, but in the end, this was a fun project to make, and I does what I need it to do.
Regardless, feel free to let me know about your feedback in the comments, and who knows, I might even work on this more and possibly even turn it into a real project.