CORE aggregates open access (OA) research papers from data providers from all over the world including institutional repositories, subject-repositories and journal publishers. OA papers are harvested allowing for search, text-mining and analytical capabilities over metadata as well as the full-text of the research papers, making CORE a unique service for the research community.
CORE currently contains over 66,000,000 open access articles, from over 6000 journals, collected from over 2300 repositories around the world. Not bad!