DSMNC is a database which provides most comprehensive catalogue of somatic SNVs occurring in single cells from various human and mouse normal tissues. Numerous non-inherited somatic mutations, distinct from those of germ-line origin, occur in somatic cells during DNA replication per cell division. The somatic mutations in normal cells, recording the unique genetic cell-lineage “history” of each proliferating cell, are also important but remain to be investigated because of their ultra-low frequency hidden in the genetic background of heterogeneous cells. Luckily, the recent development of single-cell genomics biotechnologies enables the screening and collection of the somatic mutations, especial single nucleotide variations (SNVs), occurring in normal cells. In the current version, the database collected ~0.8 million SNVs accumulated in ~600 single normal cells (579 human cells and 39 mouse cells). As the purpose of collecting somatic mutations in individual normal cells, the database DSMNC has made it possible to analyze the burdens and signatures of somatic mutations in various types of heterogeneous normal cells.