I've tried a few options over the years, including SMB and NFS, XBMC as well as HTML with javascript I found online.
I don't have a large collection of music (fewer than 100 albums), so hand coding things was actually one of the quicker options to setup. That's despite then hassle of hand coding the URL to each FLAC file as well as the album art. But sometimes the javascript doesn't handle large collections of FLAC and each implementation I tried had different quirks so I've sunk a lot of time into that in other ways without a satisfactory result.
I've heard of Emby, Jellyfin, Plex, Roon and Servio. I just need something that's simple to set up and access. I don't need fancy features beyond the ability to play the music with a pleasant UI that can be accessed from the web (HTTP, not HTTPS). I'd be running this from a Raspberry Pi 3B which already has the lighttpd server running.
I'm also considering just getting a portable, 128GB FLAC player with a minijack connection and moving on with my life without getting involved in networking at all.
Any recommendations for an uncomplicated way to approach to doing this?
Edit: Thanks so much for the helpful and enthusiastic comments! I tried Navidrome and had it up and running in ten minutes thanks to this tutorial video: https://invidious.nerdvpn.de/watch?v=7V5UUJlSknY
I had to install docker-compose on the RPi. Then I got an error which turned out to be because I also needed a separate docker daemon which I installed following these instructions: https://www.simplilearn.com/tutorials/docker-tutorial/raspberry-pi-docker
In just 10+ minutes I had my music collection accessible from all my devices - thanks again!
I used Plex for a long time but moved to Jellyfin after reading about the general direction Plex is going (trying to commercialize it, partner up with industry, make it more than just a self hosted media service).
Both have what you're looking for.
I would say Plex is slightly easier and has the benefit of PlexAmp (available for Linux, Windows, and mobile).
That being said, Jellyfin is about the same ease to get set up, but it's just a tad less polished, but in sort of a nice way. It feels more like "yours", if that makes sense.
For both, I recommend hosting them in Docker, using Docker Compose, and using the LinuxServer version. LinuxServer maintains updated software, packaged in an easy to install format and they help you out with sample Docker Compose files and explanations to get things running.