head to head · open source
koreader vs citadel
koreader has 29,761 GitHub stars, 1,908 forks, 1,345 open issues and last shipped yesterday. citadel has 1,276 stars, 20 forks, 10 open issues and last shipped yesterday. koreader leads on adoption by 2,232% (29,761 vs 1,276 stars). koreader is written in Lua under AGPL-3.0; citadel is written in Rust under MIT. koreader has attracted 6% as many forks as stars, citadel 2%. citadel was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ebook, 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
| koreader | citadel | |
|---|---|---|
| GitHub stars | ★ 30K | ★ 1.3K |
| License | AGPL-3.0 | MIT |
| Written in | Lua | Rust |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 1.9K | ⑂ 20 |
| 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 citadel if
- You want the citadel feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Rust
- You evaluated both and citadel 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 citadel
Citadel is a desktop application for managing ebook libraries, written in Rust and released under the MIT license. It is positioned inside the Calibre ecosystem as a backwards compatible manager for ebook collections, with the stated goal that Calibre must be able to read any library that Citadel has edited. The project targets users who want a faster and easier to use interface for organizing ebooks, especially epub files, without replacing the Calibre library format.
read the full citadel overview →
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Frequently asked questions
Is koreader or citadel more popular?
koreader has 29,761 GitHub stars and citadel has 1,276. koreader has the larger community by that measure.
Are koreader and citadel free?
Both are open source. koreader is licensed under AGPL-3.0 and citadel under MIT. Neither carries a licence fee.
What is the difference between koreader and citadel?
koreader is written in Lua and citadel in Rust. 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 citadel?
Choose koreader if you want the larger community (29,761 stars) or its AGPL-3.0 licence terms. Choose citadel if its feature set, stack or MIT licence fits better. Both are self-hostable.