This page is intentionally off-topic from Kindle modding. It is just a fun shoutout list of projects and apps I personally love and recommend.
Audiobookshelf is one of my favorite self-hosted apps. It is a great way to manage and stream your audiobook collection with a clean, easy interface.
I also love how flexible it is. Depending on your setup, it can fit nicely into some Kindle audio workflows too.
Still is my favorite iPhone app for Audiobookshelf. The developer is very responsive, and the UI/UX is the best iOS audiobook experience I have used so far.
Its free tier already includes the features most people need, including downloads, while some paid alternatives lock basic features behind subscriptions.
Calibre-Web is another project I strongly recommend, especially if you already use Calibre and self-host your library.
It feels like having your own Kindle-store-style interface for your personal collection. It also supports OPDS, so lots of reading apps can connect to it directly.
I will keep adding random favorites here over time whenever I find things worth shouting out.