This is an app.

Well I was thinking if the generation was done server-side, and it was the same for everyone, like an internet radio station, then I expect it would probably be pretty simple to write a free client that connects, or maybe you could even manually search the HTML for an m3u file or something and put that in VLC. Like how for Rainwave you can use VLC + https://rainwave.cc/tune_in/5.ogg.m3u to connect (Rainwave is free software though, so you can just use the website, but this also means people can listen without running any custom software, which might be more convenient for some people.).

If all the generation is done client side, then writing a free software client would be probably about as difficult as writing the application from scratch (which is to say, probably pretty difficult), and it wouldn't make much sense to connect to the original server. It also means that a free replacement program would not necessarily get the same set of music.

Do you think it would be realistic for someone to write a free software client that interfaces with this server and gets similar functionality, or is the functionality mostly client-side? Mostly just curious.

Is this free software? If so, where can I get the source code?