Sigma CRISPR/Cas technology consists of clustered, regularly interspaced, short palindromic repeat (CRISPR) RNA-guided nuclease complexes and an online design tool. The CRISPR nuclease complexes, which are packaged in single plasmid vectors containing green fluorescent protein, are used to introduce genome edits at desired sites in mammalian genomes. The online design tool is used to identify the best target site(s) within human, mouse, and rat protein-coding exons that adhere to CRISPR/Cas targeting requirements. It is meant to reduce the possibility of off-target effects by automatically applying CRISPR/Cas best-design practices, including a minimum requirement of three base-pair mismatches between the target site and other sites in the genome.