GemReader — Android EPUB reader built around highlighting and review

[cnohall]

Hi all,

I built an Android app called GemReader. It started as a normal EPUB reader, but the part I actually care about is what happens after you highlight something.

Highlights and notes ("gems") collect into a list you can filter and review later with spaced repetition. You can export them to Anki, or import an existing Anki deck. There's a built-in dictionary, TTS, and split-pane reading for when you're working across two parts of a book.

The reading side is what you'd expect: EPUB + PDF, six highlight colours, bookmarks, footnotes, search, custom fonts/themes. Fully offline. No account, no ads, no sync server. Books are encrypted on disk, and you can lock a collection behind a password.

Play Store: https://play.google.com/store/apps/d....gemreader.app
Direct APK (if you avoid Play): https://gemreader.com/download

Would love feedback on rendering quality (especially messy EPUBs and academic PDFs), and on whether the review/study flow is actually useful or just clutter. Bug reports welcome.