The core of ScienceOpen is based on a huge corpus of open access articles, drawn primarily from PubMed Central and arXiv. This forms about 2 million open access records, and each one comes with its own reference list. ScienceOpen provides a publicly available citation index that is free for researchers to use wherever they are and is provided at no cost to libraries, which in February 2016 was dubbed the Open Citation Index. Data available on research articles are analyzed, and the analysis links articles via authors, citations, keywords, journals, and more. Users can further add to the context of an article with comments, recommendations, or post-publication peer reviews. Researcher-led topical collections also provide opportunities for discovery and communication.