Zotero: Free, easy-to-use tool to collect, organize, cite, and share research
Zotero is, if you're not in the market for a closed source silo like EndNote, the only game left in town. Mendeley went full on Evil, and Papers for Mac is Mac only, closed source, and missing dozens of functionalities that are absolutely a must have in academic writing and research.An absolute must have is BetterBibTex (https://retorque.re/zotero-better-bibtex/), which adds better Citekey management and, my personal highlight, "export on add" functionality. In short, everything I save into a specific folder in my library gets exported as a .bib file right away. That way I can click a button in my browser and have the citation ready in my LaTeX editor, Word, or Obsidian (https://github.com/hans/obsidian-citation-plugin) within seconds.The latest beta also adds full Markdown export for Notes. I tend to keep my notes on papers in Zotero, attached to the paper, but export them for filing in Obsidian (which I then feed into MkDocs for our work group's large repo).Unless you need Apple Pages support, which Apple keeps to itself and only sells for mighty moolah to a select few, Zotero can do anything EndNote can do, is Open Source, and with that won't drive your PI up the wall with yet another expense.