Sounds too good to be true? It did to me too, but except for a very minor and rare glitch in adding notes to articles, the only issue I encountered happened when I was signed into two Google accounts at the same time. Logging out of both and signing in again to the one associated with Paperpile solved this completely, and the service's help files are thorough, clear, and pretty much solve any problem that may arise.
Paperpile is not free — you will have to pay $2.99/month after the first 30 days — but once you try it, you won't mind one bit. There are enough hardships in academic life without having to fight with references and citations, and Paperpile is the first service I've used that makes this truly painless. In future updates, Paperpile plans to add its own PDF annotation tools as well as better support for tablets and phones. When that happens, the service will be indespensible.
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