head to head · open source
koreader vs zlib
koreader has 30,064 GitHub stars, 1,941 forks, 1,345 open issues and last shipped today. zlib has 524 stars, 38 forks, 1 open issues and last shipped 26 days ago. koreader leads on adoption by 5,637% (30,064 vs 524 stars). koreader is written in Lua under AGPL-3.0; zlib is written in Go under MIT. koreader has attracted 6% as many forks as stars, zlib 7%. koreader was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ebook, 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.
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Side by side
| koreader | zlib | |
|---|---|---|
| GitHub stars | ★ 30K | ★ 524 |
| License | AGPL-3.0 | MIT |
| Written in | Lua | Go |
| Last push | 2026-10-03 | 2026-09-07 |
| Forks | ⑂ 1.9K | ⑂ 38 |
| 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 zlib if
- You want the zlib feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Go
- You evaluated both and zlib 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 zlib
zlib is a command line interface for Z Library that lets readers search the catalogue, download ebooks, send them to a Kindle device, and drive the whole workflow from AI coding agents.
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Frequently asked questions
Is koreader or zlib more popular?
koreader has 30,064 GitHub stars and zlib has 524. koreader has the larger community by that measure.
Are koreader and zlib free?
Both are open source. koreader is licensed under AGPL-3.0 and zlib under MIT. Neither carries a licence fee.
What is the difference between koreader and zlib?
koreader is written in Lua and zlib in Go. 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 zlib?
Choose koreader if you want the larger community (30,064 stars) or its AGPL-3.0 licence terms. Choose zlib if its feature set, stack or MIT licence fits better. Both are self-hostable.