Best Thorium Reader Alternatives in 2026
The top Thorium Reader alternatives are Foxit PDF Reader, Okular and FBReader: 15 file reader software our editors would look at instead of Thorium Reader, in our ranking order.
Thorium Reader: A format-rich reader with accessibility tools, bookmarks and annotations at no cost. Where it falls short: no official sync-across-devices claim.
Switching from Thorium Reader? For most file reader software buyers the best Thorium Reader alternative is Foxit PDF Reader, built for cross-platform PDF reading and document review.
Why People Look for a Thorium Reader Alternative
- No official sync-across-devices claim
- Focused on reading rather than broader document workflows
- Readium LCP support may not fit publications using other protections
Quick Picks by What You Need
- Best overallFoxit PDF Reader9.3
Cross-platform PDF reading and document review
Visit Foxit PDF Reader - Best free optionFoxit PDF Reader9.3
Has a free plan
Visit Foxit PDF Reader
All 15 Thorium Reader Alternatives, Ranked
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
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Best forCross-platform PDF reading and document review
- Better than Thorium Reader:
- Editor score 9.3 vs 7.9
A cross-platform PDF reader for reading, reviewing, signing and completing forms.
- Annotations
9.3/10★★★★★Visit Foxit -
Best forCross-platform PDF and document reading
- Better than Thorium Reader:
- Editor score 9.2 vs 7.9
A capable open-source reader for PDFs, e-books, annotations, forms, and accessibility tools.
- Annotations
9.2/10★★★★★Visit Okular -
Best forReaders who want broad-format ebook support
- Better than Thorium Reader:
- Editor score 9.1 vs 7.9
A format-flexible ebook reader with free desktop editions and optional paid mobile features.
9.1/10★★★★★Visit FBReader -
Best forWindows users who want a capable free reader
- Better than Thorium Reader:
- Editor score 9.0 vs 7.9
A format-flexible Windows reader with annotations, forms and portable operation at no cost.
- Annotations
9.0/10★★★★☆Visit Sumatra PDF -
Best forOpen-source readers across ebook and document formats
- Better than Thorium Reader:
- Editor score 8.8 vs 7.9
A format-flexible reader with annotations, PDF controls, and optional reading-position sync.
- Annotations
8.8/10★★★★☆Visit KOReader -
Best forEmbedding a PDF reader in a web application
- Better than Thorium Reader:
- Editor score 8.4 vs 7.9
A self-hosted PDF viewer for web apps, with navigation, annotations and forms.
- Annotations
8.4/10★★★★☆Visit Mozilla PDF.js -
Best forLinux users reading and annotating documents
- Better than Thorium Reader:
- Editor score 8.3 vs 7.9
A free Linux reader for viewing, searching, annotating, and printing documents.
- Annotations
8.3/10★★★★☆Visit GNOME Papers -
Best forAuthors preparing books for Kindle publishing
- Better than Thorium Reader:
- Editor score 8.2 vs 7.9
A free desktop formatter for authors creating Kindle and print-ready book files.
8.2/10★★★★☆Visit Kindle Create -
Best forReaders buying and listening to Kobo audiobooks
- Better than Thorium Reader:
- Editor score 8.0 vs 7.9
A Kobo storefront and player for audiobook listeners who also want eBooks.
8.0/10★★★★☆Visit Kobo -
Best forTeams needing PDF rendering and document manipulation
A cross-platform PDF toolkit for rendering, extraction, annotation, and document editing.
- Annotations
7.9/10★★★★☆Visit MuPDF -
Best forAuthors and publishers creating narrated Apple Books
A free production program for authors and publishers focused on Apple Books audiobook publishing.
7.9/10★★★★☆Visit Apple Books -
Best forImage viewers needing cataloging and metadata tools
A format-rich desktop viewer with cataloging, metadata, comparison, and batch tools.
7.9/10★★★★☆Visit XnView MP -
Best forWindows users who want broad image-format viewing
A free Windows desktop tool for viewing, organizing, and converting many image formats.
7.9/10★★★★☆Visit XnView -
Best forWindows users viewing and processing image files
A Windows image viewer with RAW support, batch tools, and a free personal-use option.
7.9/10★★★★☆Visit FastStone -
Best forWindows users who also need image batch tools
A compact Windows viewer for image conversion, resizing, and batch file operations.
7.9/10★★★★☆Visit IrfanView
Thorium Reader Alternatives: Common Questions
What is the best alternative to Thorium Reader?
Foxit PDF Reader: #1 in our File Reader Software ranking, with an editor score of 9.3 out of 10. A cross-platform PDF reader for reading, reviewing, signing and completing forms.
Is there a free alternative to Thorium Reader?
Yes. Foxit PDF Reader, Okular, FBReader, SumatraPDF and KOReader have a free plan or a free tier (15 of the 15 alternatives on this page).
Why do people look for Thorium Reader alternatives?
No official sync-across-devices claim; Focused on reading rather than broader document workflows; Readium LCP support may not fit publications using other protections.
How do I switch from Thorium Reader?
Export your data from Thorium Reader (most tools have an export in their settings). Sign up for the alternative; start on its free plan or trial if it has one. Import your export and set up the integrations your team relies on. Run both side by side for a short while, then cancel Thorium Reader.
How to Switch from Thorium Reader
- Export your data from Thorium Reader (most tools have an export in their settings).
- Sign up for the alternative; start on its free plan or trial if it has one.
- Import your export and set up the integrations your team relies on.
- Run both side by side for a short while, then cancel Thorium Reader.
Thorium Reader vs Each Alternative
| # | Tool | Free plan | Paid from | Annotations | Score |
|---|---|---|---|---|---|
| 16 | Thorium Reader | Yes | Free | Yes | 7.9 |
| 1 | Foxit PDF Reader | Yes | Free | Yes | 9.3 |
| 2 | Okular | Yes | Free | Yes | 9.2 |
| 3 | FBReader | Yes | 9.1 | ||
| 4 | SumatraPDF | Yes | Free | Yes | 9.0 |
| 5 | KOReader | Yes | Free | Yes | 8.8 |
| 6 | Mozilla PDF.js | Yes | Free | Yes | 8.4 |
| 7 | Papers | Yes | Free | Yes | 8.3 |
| 8 | Kindle Create | Yes | Free | 8.2 | |
| 9 | Kobo Books | Yes | 8.0 | ||
| 10 | MuPDF | Yes | $299/unit/mo | Yes | 7.9 |
| 11 | Apple Books Digital Narration | Yes | Free | 7.9 | |
| 12 | XnView MP | Yes | €3.90/unit one-time | 7.9 | |
| 13 | XnView Classic | Yes | Free | 7.9 | |
| 14 | FastStone Image Viewer | Yes | 7.9 | ||
| 15 | IrfanView | Yes | $18/device one-time | 7.9 |
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Last updated · How we research and update