BioReaction Universe (BRU) is a freely available biochemical reaction explorer. BRU aims to 1) integrated public biochemical database including Rhea, MetaCyc, KEGG and assign own unique identifier, 2) explore biochemical universe and finding metabolic pathway between given two metabolites, 3) predict unknwon or non-existent biochemical reactions based on reaction rule, feasiabiliy in cell, and thermodynamical knowledge.