
You pay a monthly fee for PaperPile and it only works with Google Docs. Zotero, Mendeley, Sciwheel, and PaperPile work with GoogleDocs. If you want software that's easy to learn, Zotero, and Mendeley are pretty easy to learn and use.If you want open source software, choose Zotero.If you don’t want to pay for software, consider Zotero.These points refer to EndNote, Zotero, and Mendeley: We try to monitor developments in reference managers and will provide information about significant updates in this library guide.

If you want easy online access to your references, consider.If you want to mainly work off-line on your own computer, EndNote is your best bet.

If you have saved a large collection of PDF files on your computer which you wish to add to your reference manager, Zotero, Mendeley and EndNote are all able to add them in bulk.EndNote Web/Online also permits this, but with fewer features than the desktop version.
