head to head · open source
calibre vs Openlib
calibre has 25,923 GitHub stars, 2,690 forks, 6 open issues and last shipped yesterday. Openlib has 2,474 stars, 130 forks, 87 open issues and last shipped 8 months ago. calibre leads on adoption by 948% (25,923 vs 2,474 stars). calibre is written in Python under GPL-3.0; Openlib is written in Dart under GPL-3.0. calibre has attracted 10% as many forks as stars, Openlib 5%. calibre was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ebook-reader, 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 | Openlib | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 2.5K |
| License | GPL-3.0 | GPL-3.0 |
| Written in | Python | Dart |
| Last push | 2026-09-17 | 2026-01-18 |
| Forks | ⑂ 2.7K | ⑂ 130 |
| 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 Openlib if
- You want the Openlib feature set and don't need the biggest community
- You prefer the GPL-3.0 license terms
- Your stack matches Dart
- You evaluated both and Openlib fits your workflow better
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 →
About Openlib
Openlib is an open source Android app written in Dart with Flutter that downloads and reads books from Anna’s Archive. It lives in the Flutter mobile app ecosystem and is licensed under GPL 3.0, with public source code, GitHub releases, and links to Android package pages for com.app.openlib.
read the full Openlib overview →
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Frequently asked questions
Is calibre or Openlib more popular?
calibre has 25,923 GitHub stars and Openlib has 2,474. calibre has the larger community by that measure.
Are calibre and Openlib free?
Both are open source. calibre is licensed under GPL-3.0 and Openlib under GPL-3.0. Neither carries a licence fee.
What is the difference between calibre and Openlib?
calibre is written in Python and Openlib in Dart. 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 Openlib?
Choose calibre if you want the larger community (25,923 stars) or its GPL-3.0 licence terms. Choose Openlib if its feature set, stack or GPL-3.0 licence fits better. Both are self-hostable.