Thorium Reader
Thorium Reader: A format-rich reader with accessibility tools, bookmarks and annotations at no cost. Ranked #16 of 24 in File Reader Software by our editors (7.9/10); pricing: Free plan; best for accessible EPUB and audiobook reading on desktop.
At a glance
- Editor score7.9 / 10
- PricingFree plan
- Best forAccessible EPUB and audiobook reading on desktop
- Free planYes
- Paid fromFree
- AnnotationsYes
- Facts checked23 Sep 2026
Where it wins
- Reads EPUB, PDF, DAISY and Readium or W3C audiobooks
- Read-aloud, media overlays and adjustable display settings
- Bookmarks, shareable annotations and OPDS catalog browsing
Where it doesn't
- No official sync-across-devices claim
- Focused on reading rather than broader document workflows
- Readium LCP support may not fit publications using other protections
Our verdict on Thorium Reader
Thorium Reader is a free, open-source reading application from EDRLab for readers, library patrons and students. It is suited to people who want one application for ebooks, audiobooks, comics and documents, with accessibility options alongside standard reading controls. Desktop versions run on Windows, macOS and Linux, and iOS/iPadOS availability is also indicated. Its format coverage makes it relevant to personal reading as well as library or educational collections.
Format support is a central strength: Thorium reads EPUB 2, EPUB 3, fixed-layout EPUB and PDF, plus DAISY 2.02 and DAISY 3 publications, Readium and W3C audiobooks, and Divina. It also supports publications protected with Readium LCP. Readers can browse and authenticate with OPDS catalogs, which suits organizations and individuals accessing catalog-based collections. Full-text search, read-aloud and media overlays add ways to navigate and consume publications, while display controls cover fonts, spacing, luminosity and themes. The combination is more useful for accessible reading than for general-purpose document editing.
Bookmarks preserve the current reading position, and shareable annotations support marking up publications. Thorium is free, so there are no paid tiers to weigh against those capabilities. Support channels include email and community. Its limitations matter for people who expect continuity across devices: no official sync-across-devices claim is available, so readers who need a coordinated library or reading position across desktop and mobile should compare alternatives. Choose Thorium for broad publication-format support, accessibility features and a no-cost reading app; look elsewhere if document workflows or confirmed cross-device syncing are essential.
Your product? Our editors can test Thorium Reader in depth and publish a review, labelled as paid · from $149/mo →
Thorium Reader pricing
Thorium Reader fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Supported formats | Not verified |
| Platforms | Windows, macOS, Linux, iOS/iPadOS |
| Annotations | Yes |
| Text search | Not verified |
| Accessibility support | Not verified |
| Cloud sync | Not verified |
| Deployment | Desktop, Mobile |
| Platforms | Windows, macOS, Linux, iOS |
| Support | Email, Community |
| Built for | Solo, Small business, Mid-market, Enterprise (editorial estimate) |
| Integrations | 1 integrations: OPDS catalogs |
| Pricing | Free plan |
| Website | thorium.edrlab.org |
| Facts checked | 23 Sep 2026 |
Thorium Reader integrations
Thorium Reader lists 1 integrations on its own site.
- OPDS catalogs
Alternatives to Thorium Reader
- Foxit PDF ReaderA cross-platform PDF reader for reading, reviewing, signing and completing forms.9.3
- OkularA capable open-source reader for PDFs, e-books, annotations, forms, and accessibility tools.9.2
- FBReaderA format-flexible ebook reader with free desktop editions and optional paid mobile features.9.1
See all Thorium Reader alternatives →
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Featured on iTechGuides
Thorium Reader is listed in our File Reader Software directory. Add the badge to your site — it links back to this page.
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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