ScienceHelper (download millions of papers)

general-extension

ScienceHelper is a Chrome Extension for researchers and students. Use it to download papers and articles from thousands of websites. When you find an academic paper, simply click the ScienceHelper button in your toolbar to search the web for a legal Open Access version. ScienceHelper will automatically find the DOI of the paper you are looking at and use that information to find the paper from various online sources and databases.

Screenshots from Chrome Web Store