There are 5 repositories under pdf-annotation topic.
The most Obsidian-native PDF annotation & editing tool ever.
Modular multi-screen pdf presentation viewer
Alfred Workflow to extract annotations from PDF files.
C# and VB.NET samples for Docotic.Pdf library
A React component for annotating PDF, powered by PDF.js and RecogitoJS
Search comments and highlights annotations in PDF documents.
There is already a gist available, just making it somewhat easy to use as Docker container or vagrant config, so it could be useful to others
Simple "digitial paper" for note taking and PDF annotation. Heavily inspired by Xournal.
PDF format annotation and labeling support for Label Studio
Flare is a LaTeX package and an extension to \includegraphics copying PDF annotations.
Fork of Moodle/editpdf, with custom options
Display PDFs with a pointer, make quick annotations (that automatically disappear), and zoom them
Tiny tool help creating PDF links in Adobe Illustrator.
A software for extracting pdf annotations.