Zotero

If you have saved PDFs of journal articles you can drag and drop files or folders into Zotero desktop. Articles will need to have a digital object identifier (DOI) for this to work. This will generate a reference for the article and also save a copy of the PDF in your Zotero library.

To annotate, double-click on your PDF and use the tools at the top of the document.

The free version of Zotero has a 300MB limit. There are paid for storage options, but Imperial does not provide these.