Bilingua Reader

Kalmarium

In-app purchases

About this app

Bilingua Reader is an EPUB and PDF reader for people learning a language. Open any book and every sentence appears with its translation directly underneath it, so you keep reading instead of stopping to look things up. Translation runs on your device by default: nothing you read is sent anywhere, and it works on a plane.

READ ANYTHING
- EPUB, rendered as the publisher made it, and PDF, re-flowed into readable text
- Three translation layouts: on its own line, on the same line, or off
- 59 languages offline with downloadable packs, or switch to Google Translate, DeepL, MyMemory, Azure AI Foundry, OpenRouter or your own LibreTranslate server for more fluent output
- Every translation is cached per book, so a book is only ever translated once — reopening it or scrolling back never spends an online quota twice

LEARN WHILE YOU READ
- Long-press a word to see its meaning, the sentence it came from and that sentence's translation, with pronunciation on tap
- Explain this word: grammar notes, from an on-device AI, a web search or LanguageTool
- Hide-to-reveal mode covers the translation until you tap it — read first, check afterwards
- Read aloud: the book is spoken to you, sentence by sentence, in the language you are learning, and keeps going with the screen off
- Highlights and sticky notes that live with the book, searchable across your whole library, exportable as Markdown or mirrored into Google Docs

REMEMBER WHAT YOU READ
- Save a word with a long-press or a double-tap; it is highlighted everywhere it appears, in every book, until you know it - then it turns green
- Built-in flashcards with spaced repetition (Again, Hard, Good, Easy, just like Anki), a daily target of new words you choose, and an optional daily reminder at your time
- Or send everything to AnkiDroid, with recognition and recall cards and a spoken clip on both sides; the sync runs both ways, so a word you know in Anki is green here too
- Export an Anki-ready file if AnkiDroid is not installed
- The Saved tab keeps every word and note in one place

A READER FIRST
- Scroll, half-page or true page turns of whole lines, with an optional slide animation you can switch off on e-ink
- Tap zones, a floating page button you can drag anywhere, and page turns on the volume keys and e-reader buttons
- A draggable progress strip and a visual index of every page or chapter
- Light and dark app themes, plus separate page themes with custom text, background and translation colours
- Missing covers are found for you; any cover can be replaced from your photos or a link

KEEP EVERY DEVICE ON THE SAME PAGE
- Google Drive sync for books, words, notes, settings and reading positions, in your own Drive — there is no Bilingua server
- Reading positions shared with calibre, Calibre-Web's Kobo sync, KOReader and Hardcover
- Browse and download from any OPDS catalogue: calibre, Calibre-Web, Komga, Kavita, Project Gutenberg
- Reading streaks, reading speed, flashcard reviews, words known and your practice streak in the Progress tab

PRIVATE BY DESIGN
- No account, no tracking, no ads
- Offline translation never leaves the device; the About screen states in plain words what an online provider receives when you choose one
- API keys are encrypted at rest with the Android Keystore

ONE PAYMENT, NO SUBSCRIPTION
Try everything free for 14 days from first launch, with up to two books of your own during the trial (the sample books and the guide never count). Then unlock once and keep it for good. The purchase is tied to your Google account, so it comes with you to your next phone.

Bilingua Reader comes with two short starter books and an in-app guide, so you can be reading with translations within a minute of installing. DRM-protected books cannot be opened, and a scanned PDF without a text layer cannot be translated.