REX is an online regulatory-compliance documentation search portal for food and supplement labeling regulations, guidance, policy records and other compliance information. From a single search page, users can access documentation from the three major regulatory sources: FDA guidance documents, code of federal regulations Title 21 and USDA FSIS documents. Users can search for relevant documents using full or partial words, and filter those search results by source, date range, type (draft guidance, petitions, etc.), or category (allergens, labeling, etc.). The program keeps track of frequent searches and recently accessed documents. Users can bookmark their favorite citations, make notes about page locations, and create folder hierarchies for easy, fast access.