A "Document Enhancer" provides an entity platform that ingests entity collections, information sources, topical databases, etc., and generates corresponding knowledge bases (KB's) and entity extraction services. This platform enables various user authorization scenarios for obtaining access to one or more KB's. Further, this platform processes arbitrary user content, e.g., documents, images, text fragments, speech, etc., to determine which KB's are relevant to that content. If access to relevant KB's is authorized, the Document Enhancer employs those KB's to analyze and augment the arbitrary content. Content augmentation examples include adding hyperlinks, highlighting relevant information, inserting relevant information into popups, windows, or tabs, enabling searches and services based on selected KB's, etc. An entity store maintains a library of available KB's that may be accessed by the user. Local or remote access to relevant KB's is obtained through various means, including, but not limited to, subscriptions, ad supported access, free access, etc.