QTLbase2 curates and compiles genome-wide QTL summary statistics for many human molecular traits across over 95 tissue/cell types and multiple biological conditions. The database comprises tens of millions significant genotype-molecular trait associations under different conditions. Users can visualize QTL results in phenome-wide and tissue-wide levels, and annotate their biological functions through comprehensive genomic features and functional evidence. QTLbase provides a one-stop shop of QTLs retrieval and comparison across multiple tissues and multiple layers of molecular complexity, and it will greatly help researchers interrogate the biological mechanism of causal variants and guide the direction of functional validation.