head to head · open source
koreader vs calibre
koreader has 29,761 GitHub stars, 1,908 forks, 1,345 open issues and last shipped yesterday. calibre has 25,923 stars, 2,690 forks, 6 open issues and last shipped yesterday. koreader leads on adoption by 15% (29,761 vs 25,923 stars). koreader is written in Lua under AGPL-3.0; calibre is written in Python under GPL-3.0. koreader has attracted 6% as many forks as stars, calibre 10%. koreader was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 4 topic tags (ebook, ebook-reader, epub, kindle), 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.
← all 8884 open source comparisons
Side by side
| koreader | calibre | |
|---|---|---|
| GitHub stars | ★ 30K | ★ 26K |
| License | AGPL-3.0 | GPL-3.0 |
| Written in | Lua | Python |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 1.9K | ⑂ 2.7K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick koreader if
- You weight community size — 30K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Lua
- You value the larger contributor base for long-term maintenance
pick calibre if
- You want the calibre feature set and don't need the biggest community
- You prefer the GPL-3.0 license terms
- Your stack matches Python
- You evaluated both and calibre fits your workflow better
About koreader
KOReader is a free, AGPL 3.0 licensed document viewer written in Lua that runs on e ink readers from Cervantes, Kindle, Kobo and PocketBook, on reMarkable, and on Android and desktop Linux, aimed at readers who want broader format support, finer typesetting control and better performance than the reading software shipped with their device.
read the full koreader overview →
About calibre
calibre is the official source code repository for the calibre e book manager, an open source application written in Python and released under GPL 3.0. It lives in the content and publishing ecosystem as a desktop tool for books, and it is cross platform, running on Linux, Windows and macOS. The project has been hosted on GitHub for roughly thirteen years, carries about 25,900 stars and 2,683 forks, and its home on the web is calibre ebook.com, where an About page and a screenshots page document it further.
read the full calibre overview →
More in Content & Publishing
Related comparisons
More Publishing projects
Compare either of these against the rest of the Publishing field.
Frequently asked questions
Is koreader or calibre more popular?
koreader has 29,761 GitHub stars and calibre has 25,923. koreader has the larger community by that measure.
Are koreader and calibre free?
Both are open source. koreader is licensed under AGPL-3.0 and calibre under GPL-3.0. Neither carries a licence fee.
What is the difference between koreader and calibre?
koreader is written in Lua and calibre in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, koreader or calibre?
Choose koreader if you want the larger community (29,761 stars) or its AGPL-3.0 licence terms. Choose calibre if its feature set, stack or GPL-3.0 licence fits better. Both are self-hostable.