Thorium Reader

Reading EPUB on a computer has always been slightly awkward. Calibre is an excellent library manager but a mediocre reader; retailer desktop clients demand a login, only open books bought from them, and track your reading progress; web-based readers require uploading the book.

Thorium Reader fills the "just a desktop reader" slot. It comes from EDRLab, a European non-profit that is also a significant participant in the EPUB and Readium standards ecosystem, so its format compliance is solid. BSD-3-Clause licensed.

The reading basics are all present: single or double page layout, adjustable font, size, line spacing and margins, dark mode, bookmarks, highlights, full-text search, table of contents navigation and remembered position. Imported books stay local and no account is needed.

What genuinely distinguishes it is accessibility, where its investment far exceeds its peers:

• Full screen reader support, so blind and low-vision users can read normally with NVDA, JAWS or VoiceOver.
• Built-in text-to-speech with adjustable speed, highlighting the current sentence as it reads.
• DAISY format support — the digital talking book standard designed for people with reading disabilities, which very few general-purpose readers handle at all.
• Dyslexia-friendly typography: specialized typefaces and increased letter and line spacing that measurably help some readers.

These features serve everyone, incidentally — having a book read aloud while cooking, or enlarging type and opening up line spacing when your eyes are tired.

To be clear about:

• It is not a library manager. Organizing hundreds of books, cleaning metadata, converting formats and sending to a Kindle are Calibre's jobs. Pairing them makes sense: Calibre manages the library, Thorium does the reading.
• On DRM: it supports LCP, an open digital rights scheme used mainly by European library lending, but not Kindle or other stores' proprietary DRM.
• Desktop only — there is no mobile version. For EPUB on a phone, look at KOReader.