Is there a Calibre equivalent for Audio books?

I use m4b-tool[1], tone[2] and audiobookshelf[3] together with an LG G5 H850 smartphone[8] with Bang & Olufsen Hifi-Plus Module for Audio Only and I am pretty happy with this config. For Music I use Navidrome[5] and Substreamer App[7]. Maybe I'll try out Jellyfin[4] or maybe Plex[6], but I really don't wanna go closed source.

I also thought about writing something self hosted in C# to have ONE solution for audiobooks, podcasts and music and started a small private project, but this will take a while until it is ready to release something...

You may ask: Why an LG G5 H850? Well, its relatively small and cheap (about 50 - 80 bucks used) it has an audio Jack, USB-C, you can change the battery, it can hold up to 2TB microSD storage, has an HiFi Plus module for audio enthusiasts and a descent screen. Besides that it can run lineage os...

Note: I'm the author of the first two projects :-)

[1]: https://github.com/sandreas/m4b-tool

[2]: https://github.com/sandreas/tone

[3]: https://github.com/advplyr/audiobookshelf

[4]: https://jellyfin.org/

[5]: https://www.navidrome.org/

[6]: https://www.plex.tv

[7]: https://substreamerapp.com/

[8]: https://en.wikipedia.org/wiki/LG_G5

https://openaudible.org could be considered somewhat Calibre-like. If it's more about self-hosting, media servers like https://jellyfin.org may be more interesting (although I wouldn't call those similar to Calibre).

Prologue - https://apps.apple.com/us/app/prologue/id1459223267?ls=1 for iOS works with plex and is my go to tool for the past 2 years

I have recently found Audiobookshelf which is pretty impressive. It still lacks some features (like Upload progress bar) and polish but is totally usable.

https://github.com/advplyr/audiobookshelf

This isn't what you wanted, but I've been using the Podcast Republic app as a way to organize and listen to my (usually free) audiobooks. It's android only, so only on-device and not on PC. Its audiobook support is a bit obscure, it relies on creating what they call a "virtual podcast" based on the filesystem. But once you find it it's pretty simple and fits into their UI, and you can tag / catalog your audiobooks as much as you want.

I also like its listening UI. It remembers where I last stopped and starts playing a configurable number of seconds before, remembers playback speed per book/podcast, remembers audio settings per book/podcast, has a car mode. I like it much better than Audible's UI.

Like I said its organizing UI is also nice, although I use it less, I don't collect audiobooks on my mobile, due to the limited internal capacity.

I’ve been using Plex to host audiobooks works well enough

https://github.com/seanap/Plex-Audiobook-Guide

There's audiobookshelf.

https://github.com/advplyr/audiobookshelf

Having a trivial, reliable way to strip audiobooks of their DRM might tempt me to get Audible.

Maybe it's better if i stay away from DRM.

Maybe I will burn in hell for this, but I think iTunes does quite a good job with organizing audiobooks.

I just stick them in Jellyfin.

It's not particularly well optimised for audiobooks, but it is nice having all my media in the same place (it also has my movies and music).