head to head · open source
calibre vs so-novel
calibre has 25,953 GitHub stars, 2,697 forks, 6 open issues and last shipped today. so-novel has 8,157 stars, 726 forks, 26 open issues and last shipped 2 months ago. calibre leads on adoption by 218% (25,953 vs 8,157 stars). calibre is written in Python under GPL-3.0; so-novel is written in Java under AGPL-3.0. calibre has attracted 10% as many forks as stars, so-novel 9%. calibre was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (ebook), 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 | so-novel | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 8.2K |
| License | GPL-3.0 | AGPL-3.0 |
| Written in | Python | Java |
| Last push | 2026-09-20 | 2026-07-26 |
| Forks | ⑂ 2.7K | ⑂ 726 |
| 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 so-novel if
- You want the so-novel feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches Java
- You evaluated both and so-novel 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 so-novel
So Novel is an AGPL 3.0 Java tool that extracts structured content from web pages and exports it as standard ebook and document formats including EPUB, TXT, and PDF, built for people who want offline copies of web fiction and for anyone turning web content into readable documents.
read the full so-novel overview →
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Frequently asked questions
Is calibre or so-novel more popular?
calibre has 25,953 GitHub stars and so-novel has 8,157. calibre has the larger community by that measure.
Are calibre and so-novel free?
Both are open source. calibre is licensed under GPL-3.0 and so-novel under AGPL-3.0. Neither carries a licence fee.
What is the difference between calibre and so-novel?
calibre is written in Python and so-novel in Java. 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 so-novel?
Choose calibre if you want the larger community (25,953 stars) or its GPL-3.0 licence terms. Choose so-novel if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.