I know the Zotero connector did something similar but I can’t get over how neatly this works in ReadCube. The pop up bar at the bottom appears whenever you open a PDF on the website of a participating publisher. To do my current literature review, I’m going through this process on my laptop and then when I open Readcube on my iPad, they’re all immediately synced with full bibliographical details and ready to read away from my laptop. The software has many other virtues but this is the first time I’ve ever experienced finding academic literature to be as seamless a process as writing a blog post or scheduling a tweet is for me. I hadn’t realised quite how much of a hassle I’d subliminally come to regard as being an unavoidable part of finding, reading and filing journal articles.