head to head · open source
calibre vs thorium-reader
calibre has 26,327 GitHub stars, 2,743 forks, 6 open issues and last shipped yesterday. thorium-reader has 2,928 stars, 245 forks, 206 open issues and last shipped yesterday. calibre leads on adoption by 799% (26,327 vs 2,928 stars). calibre is written in Python under GPL-3.0; thorium-reader is written in TypeScript under BSD-3-Clause. calibre has attracted 10% as many forks as stars, thorium-reader 8%. thorium-reader was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (epub), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| calibre | thorium-reader | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 2.9K |
| License | GPL-3.0 | BSD-3-Clause |
| Written in | Python | TypeScript |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 2.7K | ⑂ 245 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick calibre if
- You weight community size — 26K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick thorium-reader if
- You want the thorium-reader feature set and don't need the biggest community
- You prefer the BSD-3-Clause license terms
- Your stack matches TypeScript
- You evaluated both and thorium-reader fits your workflow better
About calibre
calibre calibre is an e book manager. It can view, convert, edit and catalog e books in all of the major e book formats. It can also talk to e book reader devices. It can go out to the internet and fetch metadata for your books. It can download newspapers and convert them into e books for convenient reading. It is cross platform, running on Linux, Windows and macOS. For more information, see the calibre About page. Screenshots Screenshots page Usage See the User Manual. Development Setting up a development environment for calibre. A tarball of the source code for the current calibre release. Bugs Bug reports and…
read the full calibre overview →
About thorium-reader
Thorium Reader Thorium Reader is an easy to use EPUB reading application for Windows 10/10S, MacOS and Linux. After importing e books from a directory or OPDS feed, you'll be able to read on any screen size, customize layout settings, navigate via the table of contents or page list, set bookmarks ... A great care is taken to ensure the accessibility of the application for visual impaired people using NVDA, JAWS or Narrator. Free application. No ads. No private data flowing anywhere. This project is in constant evolution, corrections and new features will be added soon and your support is welcome for that. The…
read the full thorium-reader overview →
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Frequently asked questions
Is calibre or thorium-reader more popular?
calibre has 26,327 GitHub stars and thorium-reader has 2,928. calibre has the larger community by that measure.
Are calibre and thorium-reader free?
Both are open source. calibre is licensed under GPL-3.0 and thorium-reader under BSD-3-Clause. Neither carries a licence fee.
What is the difference between calibre and thorium-reader?
calibre is written in Python and thorium-reader in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, calibre or thorium-reader?
Choose calibre if you want the larger community (26,327 stars) or its GPL-3.0 licence terms. Choose thorium-reader if its feature set, stack or BSD-3-Clause licence fits better. Both are self-hostable.