head to head · open source
calibre vs vmprint
calibre has 25,923 GitHub stars, 2,690 forks, 6 open issues and last shipped yesterday. vmprint has 676 stars, 30 forks, 1 open issues and last shipped 20 days ago. calibre leads on adoption by 3,735% (25,923 vs 676 stars). calibre is written in Python under GPL-3.0; vmprint is written in JavaScript under Apache-2.0. calibre has attracted 10% as many forks as stars, vmprint 4%. calibre was the more recently maintained of the two, and both are self-hostable with no licence fee.
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 | vmprint | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 676 |
| License | GPL-3.0 | Apache-2.0 |
| Written in | Python | JavaScript |
| Last push | 2026-09-17 | 2026-08-29 |
| Forks | ⑂ 2.7K | ⑂ 30 |
| 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 vmprint if
- You want the vmprint feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches JavaScript
- You evaluated both and vmprint 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 vmprint
VMPrint is an Apache 2.0 layout engine written in JavaScript that decides where every glyph goes and returns a flat array of exact X/Y coordinates, built for teams creating Canvas or WebGL tools, high volume report generators, print on demand pipelines, document editors, and edge runtime deployments.
read the full vmprint overview →
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Frequently asked questions
Is calibre or vmprint more popular?
calibre has 25,923 GitHub stars and vmprint has 676. calibre has the larger community by that measure.
Are calibre and vmprint free?
Both are open source. calibre is licensed under GPL-3.0 and vmprint under Apache-2.0. Neither carries a licence fee.
What is the difference between calibre and vmprint?
calibre is written in Python and vmprint 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 vmprint?
Choose calibre if you want the larger community (25,923 stars) or its GPL-3.0 licence terms. Choose vmprint if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.