MuPDF is a free and open-source software framework written in C that implements a PDF, XPS, and EPUB parsing and rendering engine. It is used primarily to render pages into bitmaps, but also provides support for other operations such as searching and listing the table of contents and hyperlinks. Developed by Artifex Software, Inc.
License: Open Source
MuPDF is a lightweight, open-source PDF viewer and toolkit known for its speed and rendering capabilities, while Skim is a user-friendly PDF reader specializing in annotation and syncing features for academic users. While MuPDF excels in performance and file format support, Skim offers better annotation tools and a more intuitive user experience.