Readest

Readest is an open‑source application for viewing EPUB and PDF documents. It runs on macOS, Windows, Linux, Android, iOS and the Web, offering a unified interface for reading across desktop, mobile and browser environments. The core functionality includes highlighting, bookmarking, note‑taking and full‑text search within a personal library.

The reader supports split‑screen “Parallel Read”, allowing two books or documents to be displayed side by side with synchronized scrolling, which is useful for comparing texts, translations or related sources. Users can customize themes, fonts, line spacing and colors, and can invoke built‑in tools to translate passages via DeepL or look up terms on Wikipedia without leaving the page. An AI‑powered text‑to‑speech engine provides audible playback of any ebook.

All annotations, bookmarks and reading progress are stored in the cloud and automatically synchronized between devices, so a user can continue where they left off on any platform. The software is positioned for students, researchers, language learners and anyone who reads multiple texts concurrently.