This document describes BiomarkerBase, a manually curated database that aggregates information on biomarkers from publicly available sources and links them together by target, disease, drug, therapeutic area, and company. It provides access to biomarker information not found through public searches and addresses limitations in public sources by standardizing nomenclature and allowing for more comprehensive querying. BiomarkerBase is used by diagnostic companies, drug companies, life science companies, and research institutions for applications like product development, clinical trial planning, and licensing.