...To this end, a flexible sgRNA design program named “CRISPR-offinder” was developed. The most important feature of this new program is that it supports all known PAM types, as well as the customer-defined PAM. Besides, CRISPR-offinder can find and rank the candidate sgRNAs in genome by off-target sites number, and also can be used to design single or paired-gRNAs. CRISPR-offinder is freely available as a command-line program or accessible via our website.