Sioyek is a PDF viewer designed for textbooks and research papers. It offers features such as quick search and open recent files, table of contents navigation, smart jump to figures or bibliography items, and customizable key bindings. Unique features include marks for quick navigation within a document, bookmarks for global notes, and portals for linking paragraph references to external figures. Build instructions are provided for Linux, Windows, and macOS systems. Users can also donate to support further development. Third-party installers are available, but come with a disclaimer to use at your own risk. Overall, Sioyek offers a robust set of features for academic PDF viewing.
https://github.com/ahrm/sioyek