To address the aforementioned issues, we herein developed a database called CAUSALdb, in which we curated and collected the majority of the published GWASs having complete summary statistics and performed statistical fine-mapping using three commonly used tools. CAUSALdb allows users to explore causal signatures across studies on variant-, gene- and trait-levels. By integrating comprehensive functional annotation resources, we constructed a highly interactive viewer to visualize and annotate potential causal variants for each trait/disease. CAUSALdb is free and open access: http://mulinlab.org/causaldb or http://mulinlab.tmu.edu.cn/causaldb.