head to head · open source
calibre vs foliate-js
calibre has 25,923 GitHub stars, 2,690 forks, 6 open issues and last shipped yesterday. foliate-js has 1,112 stars, 265 forks, 61 open issues and last shipped 5 months ago. calibre leads on adoption by 2,231% (25,923 vs 1,112 stars). calibre is written in Python under GPL-3.0; foliate-js is written in JavaScript under MIT. calibre has attracted 10% as many forks as stars, foliate-js 24%. calibre was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (ebook, 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 | foliate-js | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 1.1K |
| License | GPL-3.0 | MIT |
| Written in | Python | JavaScript |
| Last push | 2026-09-17 | 2026-05-01 |
| Forks | ⑂ 2.7K | ⑂ 265 |
| 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 foliate-js if
- You want the foliate-js feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches JavaScript
- You evaluated both and foliate-js 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 foliate-js
foliate js is a pure JavaScript library for rendering e books directly in the browser, built for developers who want to embed a reader in a web application without a backend conversion step or a native rendering stack.
read the full foliate-js overview →
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Frequently asked questions
Is calibre or foliate-js more popular?
calibre has 25,923 GitHub stars and foliate-js has 1,112. calibre has the larger community by that measure.
Are calibre and foliate-js free?
Both are open source. calibre is licensed under GPL-3.0 and foliate-js under MIT. Neither carries a licence fee.
What is the difference between calibre and foliate-js?
calibre is written in Python and foliate-js in JavaScript. 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 foliate-js?
Choose calibre if you want the larger community (25,923 stars) or its GPL-3.0 licence terms. Choose foliate-js if its feature set, stack or MIT licence fits better. Both are self-hostable.