scICB is a pan-cancer scRNA-seq database specifically designed for studying immune checkpoint blockade (ICB) therapy in human tumors, featuring over 3 million high-quality single-cell transcriptomes across 13 cancer types. In addition to standard analyses such as dimensionality reduction, clustering, and consensus cell type annotation (Browse Module), a key feature of scICB is its detailed clinical information for each sample, including patient ID, tissue origin (tumor, PBMC, adjacent normal tissue, and tumor-draining lymph nodes), sampling timepoints relative to immunotherapy (Pre and Post ICB treatment), drug types, and efficacy assessments based on radiographic or pathological criteria (responders or non-responders). By integrating this carefully curated clinical data, users can easily filter by cancer type, project, cell type subgroup, and tissue type, then perform differential gene expression and functional enrichment analyses based on treatment timepoints (Pre vs. Post Module) or therapeutic responses (R vs. NR Module) to identify potential biomarkers predictive of ICB efficacy. This offers a comprehensive understanding of the molecular mechanisms underlying the heterogeneity of immunotherapy responses across different cancers, with significant implications for future clinical applications. Additionally, users can upload custom gene sets to analyze specific changes before and after ICB treatment, or between R and NR groups, enhancing the database’s flexibility and utility.