Tropy, a sister project of the Zotero bibliography manager, is an open source program for managing and annotating research images and PDFs. For a thorough introduction to all of Tropy’s useful features, check out this recording of a webinar about Tropy that we announced earlier.
EUI Library. Introduction to Tropy. 2021. YouTube, https://www.youtube.com/watch?v=yuxlkRlFwhI.