Thorium Reader

thorium.edrlab.org ↗

An open-source desktop reading and annotation app

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SI Score: 75/100
Pricing: Not confirmed
Free plan: Yes AI reading, not confirmed
Sign-up required: Not confirmed

ebook-readers desktop-reading

Ask SI about Thorium Reader

Answers use saved listing facts and recorded sources.

What it does

Thorium Reader is a free, open-source desktop reader with selection, annotation and classification tools. Official builds cover Windows, Mac and Linux.

Choose the installer for your operating system and processor before importing reading material. Thorium is useful when you want a desktop reading workflow with annotations rather than a phone-first app. Check the stated minimum operating system, especially on an older school or library computer.

EDRLab lists EPUB, PDF and DAISY among the supported publications, plus Readium LCP-protected books. OPDS catalogue access and shareable annotations are included; a retailer using another protection system still needs a compatibility check.

Strengths

Free desktop reader
Several operating-system and processor builds

Best for

Reading and annotating on a desktop computer

Sources

Thorium Reader (Oct 26, 2026)
Thorium Reader capabilities | EDRLab (Oct 26, 2026)

SI Score

75/100

#62 in Books & Reading

Based on published information. No hands-on task test.

Method 2.0 · Published source review Assessed Oct 26, 2026Score ceiling for this evidence: 84/100.

Product usefulness 75

Evidence

The official pages document desktop/architecture choices and supported publication/annotation controls with specific LCP compatibility. This supports selecting a reading setup without claiming every DRM scheme or file is supported.

Limits: AI review of saved source passages. No hands-on test, human approval or automatic-provider checker receipt.

Source links and check dates are in Sources and checks below.

Separate website checks

These checks do not add points to the SI Score. They inspect the website's HTML, not the product in use.

Basic website checksunknown

No check recorded.

HTML accessibility checksunknown

No check recorded.

Homepage HTML responseunknown

No check recorded.

Trackers in homepage HTMLunknown

No check recorded.

Page date hintsunknown

No check recorded.

Policy links do not verify a company's conduct. An HTML response time is not application speed. Tracker and accessibility checks miss behavior after page load. Copyright dates do not prove product upkeep.

How the SI Score works →

Unconfirmed details may be unassessed, absent from the pages checked or temporarily unreadable. A missing price does not mean the service is free.

Sources and checks

Supporting pages for product usefulness, site facts, prices and separate website checks. Each record keeps its own date. Reading a page does not establish how well the product performs in use.

thorium.edrlab.org/en/
- Free planAI reading, not confirmedChecked Oct 26, 2026
  The landing page explicitly labels the application completely free.
- PlatformsAI reading, not confirmedChecked Oct 26, 2026
  The landing page explicitly supplies builds for Windows, macOS and Linux.
- Open sourceAI reading, not confirmedChecked Oct 26, 2026
  The landing page explicitly describes the reader as open source.
- Product usefulness evidenceChecked Oct 26, 2026
www.edrlab.org/software/thorium-reader/
- Product usefulness evidenceChecked Oct 26, 2026

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