CellMarker is a manually curated database that provides a comprehensive and accurate resource of cell markers for various cell types in human and mouse tissues. The database was developed to address the lack of a centralized resource for cell markers identified through single-cell RNA sequencing and experimental studies. By curating over 10,000 published papers, CellMarker records 4124 entries, including cell marker information, tissue type, cell type, cancer information, and source. The final database includes 13,605 cell markers for 467 cell types in 158 human tissues/sub-tissues and 9148 cell markers for 389 cell types in 81 mouse tissues/sub-tissues. CellMarker offers a user-friendly interface for browsing, searching, and downloading markers, and provides a summarized marker prevalence graph for each cell type. The database is regularly updated to incorporate new findings from single-cell RNA sequencing studies and other research. CellMarker is expected to be a valuable resource for researchers in cell biology, particularly in single-cell studies, by aiding in the precise identification and characterization of cells.CellMarker is a manually curated database that provides a comprehensive and accurate resource of cell markers for various cell types in human and mouse tissues. The database was developed to address the lack of a centralized resource for cell markers identified through single-cell RNA sequencing and experimental studies. By curating over 10,000 published papers, CellMarker records 4124 entries, including cell marker information, tissue type, cell type, cancer information, and source. The final database includes 13,605 cell markers for 467 cell types in 158 human tissues/sub-tissues and 9148 cell markers for 389 cell types in 81 mouse tissues/sub-tissues. CellMarker offers a user-friendly interface for browsing, searching, and downloading markers, and provides a summarized marker prevalence graph for each cell type. The database is regularly updated to incorporate new findings from single-cell RNA sequencing studies and other research. CellMarker is expected to be a valuable resource for researchers in cell biology, particularly in single-cell studies, by aiding in the precise identification and characterization of cells.