Kopernio is a literature search and retrieval tool that helps researchers find and download PDFs from legally authorized sources such as publishers, open access repositories, and other document archives. Kopernio is a free web browser plugin that you install with Chrome or Firefox. More information on setting up an account can be found here.
Kopernio works with Vanderbilt's subscriptions to bring you paywalled articles that you (using your VU credentials) are entitled to access. If no subscription access is available, Kopernio will try to deliver a free alternative, e.g. an OA version or preprint.
A recent article in Nature describes the benefits of using Kopernio to retrieve research papers you find as you travel the Web.
For more information, get in touch with your research librarians.