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 versatile and lightweight document viewer with robust features for rendering and searching across various formats, making it suitable for users who need advanced functionalities. In contrast, STDU Viewer offers a more user-friendly interface focused on basic viewing and annotation capabilities, making it ideal for casual users.