head to head · open source
calibre vs PolyglotPDF
calibre has 25,923 GitHub stars, 2,690 forks, 6 open issues and last shipped yesterday. PolyglotPDF has 1,321 stars, 198 forks, 14 open issues and last shipped 12 months ago. calibre leads on adoption by 1,862% (25,923 vs 1,321 stars). calibre is written in Python under GPL-3.0; PolyglotPDF is written in Python under GPL-3.0. calibre has attracted 10% as many forks as stars, PolyglotPDF 15%. 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 | PolyglotPDF | |
|---|---|---|
| GitHub stars | ★ 26K | ★ 1.3K |
| License | GPL-3.0 | GPL-3.0 |
| Written in | Python | Python |
| Last push | 2026-09-17 | 2025-09-28 |
| Forks | ⑂ 2.7K | ⑂ 198 |
| 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 PolyglotPDF if
- You want the PolyglotPDF feature set and don't need the biggest community
- You prefer the GPL-3.0 license terms
- Your stack matches Python
- You evaluated both and PolyglotPDF 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 PolyglotPDF
PolyglotPDF is a Python based multilingual eBook and PDF processing tool for translating documents while preserving original layout. It targets scanned and digital PDFs, and it sits in the content publishing ecosystem as an open source layout preserving translator. The README describes specialized techniques for recognizing text, tables, and formulas in PDF documents, with processing typically completed within one second and full document translations usually completed within ten seconds depending on the translation API provider.
read the full PolyglotPDF overview →
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Frequently asked questions
Is calibre or PolyglotPDF more popular?
calibre has 25,923 GitHub stars and PolyglotPDF has 1,321. calibre has the larger community by that measure.
Are calibre and PolyglotPDF free?
Both are open source. calibre is licensed under GPL-3.0 and PolyglotPDF under GPL-3.0. Neither carries a licence fee.
What is the difference between calibre and PolyglotPDF?
calibre is written in Python and PolyglotPDF in Python. 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 PolyglotPDF?
Choose calibre if you want the larger community (25,923 stars) or its GPL-3.0 licence terms. Choose PolyglotPDF if its feature set, stack or GPL-3.0 licence fits better. Both are self-hostable.