- Multi-format Support: Reads EPUB 2, EPUB 3, fixed-layout EPUBs, PDFs, DAISY books, audiobooks, and Divina publications.
- Accessibility First: Optimized for screen readers like NVDA, JAWS, and VoiceOver, supporting visually impaired and dyslexic readers.
- LCP DRM Compatibility: Opens LCP-protected EPUBs, PDFs, audiobooks, and other supported formats.
- Advanced Reading Controls: Customize fonts, spacing, colors, brightness, columns, and reading modes including night and sepia.
- OPDS Catalog Browsing: Browse, authenticate, and borrow from OPDS 1 and 2 digital library catalogs.
- Read Aloud & Media Overlays: Supports synchronized text-to-speech and EPUB media overlays.
- Annotations & Bookmarks: Create shareable annotations, bookmarks, and manage reading positions.
Edrlab Thorium Reader
Free, open-source, highly accessible EPUB and digital publication reader
Updated August 11, 2026
Edrlab Thorium Reader Overview
Thorium Reader is an open-source desktop reading app for EPUB, PDF, DAISY, audiobooks, and other digital publications. It runs on Windows, macOS, and Linux.
Accessibility is central to the app, with screen-reader support, reading controls, read-aloud tools, and support for protected publications. Library users can also browse OPDS catalogs, while bookmarks and annotations help with longer reading projects.
Key Features
Pricing
| Plan | Price | Featured |
|---|---|---|
| Thorium Reader | $0 (free and open source) | EPUB, PDF, DAISY, audiobooks, and accessibility features |
Thorium Reader is free and open source. Donations support development but are not a required plan or subscription.
Pricing source: EDRLab Thorium Reader
Pros
| Compared with | Why this product may fit better |
|---|---|
| Adobe Digital Editions | Thorium Reader is open source and gives accessibility a central place, including DAISY support and screen-reader work. Adobe Digital Editions is more tied to Adobe's ebook ecosystem. |
| Calibre | Thorium Reader offers a cleaner reading-focused experience for EPUB, DAISY, PDF and audiobooks. Calibre is stronger at library management and conversion, but that makes its interface busier for someone who only wants to read. |
| Bookworm | Thorium Reader runs on Windows, macOS and Linux and handles accessible publishing formats. Bookworm is a simpler Linux reader, so Thorium is easier to standardize across a mixed desktop fleet. |
Cons
| Compared with | Where this product may fall short |
|---|---|
| Adobe Digital Editions | Adobe Digital Editions remains the familiar route for books protected with Adobe DRM. Thorium focuses on LCP and open reading standards, so it will not replace every publisher-specific workflow. |
| Calibre | Calibre can organize a large library, edit metadata and convert formats. Thorium Reader does not try to manage that whole collection, which means heavy ebook users may need both programs. |
| Bookworm | Bookworm has a smaller, more native-feeling footprint on Linux. Thorium Reader is Electron-based, and reviewers have noticed the extra memory use on modest hardware. |
Reviews
- Reddit r/software discussion: One commenter confirmed that Thorium handled vertical Japanese EPUBs and praised its DAISY, PDF and accessibility support. Other participants disliked the LCPL reading experience and the memory use of its Electron desktop build.
- Erdal Ozkaya review: The review highlights text to speech, dyslexic-font options, screen-reader support and EPUB 3 or DAISY compatibility. It also reports slower behavior on large or complex books, limited visual customization and no mobile version.
- Klaava review: Klaava liked Thorium's two-page view on a large screen and the option to scroll an ebook like a webpage. The review also singled out the reader's privacy stance rather than claiming it was a full library manager.
