The PDF engine behind our tools: PyMuPDF & MuPDF
Most of our PDF tools — merge, split, rotate, compress, convert — are powered by one remarkable open-source library. Here's the story behind PyMuPDF and the MuPDF engine, and what its licence means.
One engine behind many tools#
When you merge, split, rotate, compress or rasterise a PDF on WebToolMart, the heavy lifting is done by PyMuPDF — the Python binding for the MuPDF engine. In our code it is imported under its historical name, fitz.
Where MuPDF came from#
MuPDF is a small, fast PDF and XPS engine written in C. It is developed by Artifex Software — the same company behind Ghostscript — and has been around since the mid-2000s. Its goal has always been the same: render and manipulate PDF pages accurately while staying light enough to embed almost anywhere, from e-readers to servers.
PyMuPDF: Python on top of MuPDF#
PyMuPDF brings that engine to Python. It was originally created by Jorj X. McKie and first published on PyPI around 2016 — its module name fitz is a nod to the original graphics library at MuPDF's core. Today it is actively maintained with support from Artifex, ships frequent releases, and is one of the most widely used PDF libraries in the Python ecosystem.
Why we chose it#
Three reasons: it is fast, it is accurate, and it does almost everything. A single library lets us read, write, merge, split, rotate, re-compress and render PDF pages to images without stitching together half a dozen tools. That reliability is why your files come back correct, every time.
A note on the licence (AGPL-3.0)#
PyMuPDF and MuPDF are released under the GNU AGPL-3.0, with a commercial licence available from Artifex. The AGPL is a strong copyleft licence: if you build a network service on top of it, you are expected to make your corresponding source available under the same terms. We take that seriously and credit every library we use — you can see the licence of each one in the Built with panel on every tool page.
Frequently asked questions
Which tools use PyMuPDF?
Our Merge, Split, Rotate, Compress and PDF to Images tools are all built on PyMuPDF.
Is PyMuPDF free?
Yes — it is open source under the AGPL-3.0 licence, with a commercial option for closed-source use.
What does “fitz” mean?
It is the original name of the graphics library at the heart of MuPDF; PyMuPDF kept it as its import name for historical reasons.