Open Source Apps with 'PDF annotation' feature for Windows
Okular is a universal document viewer developed by KDE. Okular works on multiple platforms, including but not limited to Linux, Windows, Mac OS X, *BSD, etc.
Polar is a powerful desktop app for managing all your web content, books, and notes. Polar keeps all your content in one place, supports tagging, annotation, highlighting and keeps track of your reading progress. .
Qiqqa is a free research and reference manager. Search for, read and annotate your PDFs. Then review your work, write up and create bibliographies instantly.
Xournal++ is a hand note taking software written in C++ with the target of flexibility, functionality and speed.
Label any type of data, images, text, or documents, in an easy-to-use open-source web interface or desktop app.
MrWriter fork. It has the ability to annotate PDF files and has a few other options.No screenshots yet
Dual screen pdf presentation software. This Qt5-based presentation viewer shows a presentation and notes for the speaker in two separate windows. Presentation and notes can be separate pdf files or combined in one file.