calibre-web as a web front-end to calibre is what Ive been using.

As a few people have pointed out, Kavita is a solid one. I ultimately used it because it saves your spot in the book server-side instead of with the browser (like calibre-web) so you can pick up where you left off on different devices.

Also has a pretty good PWA for your phone if you want to read on there.

I use calibre and calibre-web. I have the DeDRM and ACSM plug-ins installed in calibre so I can buy a book from ebooks.com or wherever, drop the acsm file in my auto import folder, then just download the drm stripped epub from calibre-web and import to the Books app on my iPad.

At the moment I am trying Kavita reader, but I don't know maybe there are better ones out there

Apparently Plex and Emby (Jellyfin) do audio book sorting, but Ive never been able to get them to work right

Calibre is highly regarded and works well with nearly all e-readers afaik. It has a local server option for browsing, uploading/downloading, and community extensions.