Quire

Quire is a native Android EPUB reader for people who self-host
calibre-web.

It browses your library over OPDS, downloads books on demand, renders
them with Readium, and syncs reading progress (and later bookmarks) to
a small companion server you run yourself (Quire Server, included).

Features:
- OPDS catalog browsing and search
- EPUB reading with Readium (font, theme, line-height controls)
- Reading progress sync across devices via your own Postgres
- Multi-user from day one
- One credential: your existing calibre-web account

Privacy:
- No analytics, no crash reporting, no third-party SDKs
- Network calls go to your calibre-web and your sync server only
- Credentials stored in Android Keystore

Source code, server, and documentation:
https://github.com/vitofico/quire

Optional AI features (off by default): when your Quire Server administrator
configures an AI endpoint (such as a self-hosted Ollama or a third-party
provider) and you opt in from Settings, Quire shows generated book
insights — author, summary, series, themes, craft notes, comparative
anchors, and book-club style discussion prompts — grounded with
citations from Wikipedia and OpenLibrary. A separate Library Insights
screen builds a personal reader profile from your finished books and
suggests further reads (both from your own library and via OpenLibrary
discovery). No AI request leaves your network until you explicitly opt
in, and a single tap in Settings deletes the cached profile.