BeeRef
Description: BeeRef is a free and open source bibliography management software. It allows you to easily organize and manage bibliographic references for papers, articles, books, and other publications. Key features include importing references from online databases, organizing references into collections, annotating PDFs, and generating citations and bibliographies.
Type: software
Pricing: Open Source
Notability
Description: Notability is a popular note-taking and annotation app for iOS and macOS. It allows users to take handwritten notes, type notes, record audio, annotate PDFs and more. Key features include advanced organization with search and tagging, auto-backup to the cloud, and easy sharing options.
Type: software
Pricing: Paid