Ive not looked into it so I don't know what kind of challenges they face. Theoretically, I don't see where the problem is though..

The primary input is a users "wishlist" of things they want. Each thing is then compared against a master list which confirms it exists and when it should be available (metadata). This is optional, but offers a more rich experience. Lastly, each thing is queried against a torrent index to try and find it. Its a relatively simple procedure. I guess the only question is whether books appear on these indices or not.

After a quick glance at the notice on their site, it seems metadata was the problem.. or more precisely, no work was being done to move to a new provider. It kinda reads like they lost steam and stopped developing it.

Apparently the folks from the rreading-glasses repo accuse Chaptarr of being vibe coded, can find it directly in their README.

For the unaware rreading-glasses is a rebuilt metadata server for Readarr, also happens to be endorsed by Readarr/Servarr, just switch it out and you’re good to go. However, Readarr won’t receive anymore feature updates or bug fixes it seems.

It's a real shame because Readarr did work and they really just needed to fix their own metadata servers. No? Or were there other problems I'm not aware of?

Yeah, I still use the latest readarr builds with both ebooks and audiobook, and with rreading-glasses they still work. I am also in the chaptarr discord and got access to the alpha build, which looks really promising. Still rough around the edges, though.

They would be willing to reopen it if people show up to develop it. The problem is that seemingly noone is invested enough to keep it going.

Audiobook shelf is great, and they have several good client apps in addition to the browser app.