head to head · open source
PyMuPDF vs substance
PyMuPDF has 10,744 GitHub stars, 800 forks, 58 open issues and last shipped 4 days ago. substance has 2,733 stars, 121 forks, 41 open issues and last shipped 6 months ago. PyMuPDF leads on adoption by 293% (10,744 vs 2,733 stars). PyMuPDF is written in Python under AGPL-3.0; substance is written in JavaScript under MIT. PyMuPDF has attracted 7% as many forks as stars, substance 4%. PyMuPDF 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
| PyMuPDF | substance | |
|---|---|---|
| GitHub stars | ★ 11K | ★ 2.7K |
| License | AGPL-3.0 | MIT |
| Written in | Python | JavaScript |
| Last push | 2026-09-17 | 2026-04-02 |
| Forks | ⑂ 800 | ⑂ 121 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick PyMuPDF if
- You weight community size — 11K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick substance if
- You want the substance feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches JavaScript
- You evaluated both and substance fits your workflow better
About PyMuPDF
PyMuPDF is a high performance Python library, built on the MuPDF C engine, for extracting, analysing, converting, rendering and manipulating PDF and other documents, aimed at Python developers building data extraction, document processing and AI retrieval pipelines.
read the full PyMuPDF overview →
About substance
Substance is a JavaScript library for web based content editing. It lives in the JavaScript and Content & Publishing / Publishing ecosystem, and it is distributed under the MIT license. The README describes it as a library that provides building blocks for realizing custom text editors and web based publishing systems, and it was developed to power the online editing platform Substance.
read the full substance overview →
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Frequently asked questions
Is PyMuPDF or substance more popular?
PyMuPDF has 10,744 GitHub stars and substance has 2,733. PyMuPDF has the larger community by that measure.
Are PyMuPDF and substance free?
Both are open source. PyMuPDF is licensed under AGPL-3.0 and substance under MIT. Neither carries a licence fee.
What is the difference between PyMuPDF and substance?
PyMuPDF is written in Python and substance 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, PyMuPDF or substance?
Choose PyMuPDF if you want the larger community (10,744 stars) or its AGPL-3.0 licence terms. Choose substance if its feature set, stack or MIT licence fits better. Both are self-hostable.