Folio Reader started with a simple idea.

A PDF can be more than a document to finish. It can be the place where you discover the next word worth learning.

Folio Reader is an Android application built in Kotlin with Jetpack Compose and Material 3. Its core reading, vocabulary, OCR, local data, and offline translation workflows are designed to keep useful learning close to the document.

Designed around reading

Instead of separating reading from study, Folio puts vocabulary discovery and review directly into the reading loop: notice a word, understand it, save it, and revisit it later.

Local-first foundations

Reading state, vocabulary, cached definitions, and preferences are stored locally on the device. Optional services such as Gemini explanations and Nearby Connections classroom activities are kept separate from the core local reading workflow.

Android-first

Folio is an Android app targeting API 35 with a minimum supported API of 26. It uses Room for local data, ML Kit for OCR and translation, PDFBox for PDF text extraction, Hilt for dependency injection, and Nearby Connections for Classroom mode.