MACdb is a comprehensive knowledgebase based totally on manual curation of cancer metabolic literature, providing high quality metabolite associations, online visualizing networks, and other effective tools for cancer or metabonomics researches. MACdb has curated 40,710 metabolite-cancer associations, covering 269 traits which were extracted from 1,127 studies reported in462 publications (17 cancer categories). knowledge graph is implemented to comprehensively evaluate and visualize associations from metabolite, trait, cancer levels. MACdb embeds an online tool for PubChem Cid mapping and Enrichment analysis, which are helpful for users to standardize and enrich metabolites with no requirement of bioinformatics skills. Users can download all associations from the downloads or the APIs page.