CHOPCHOP is a web tool for selecting target sites for CRISPR/Cas9, CRISPR/Cpf1 or TALEN-directed mutagenesis.

CHOPCHOP can be run with as few as three basic input options, or with additional advanced parameters. The basic input comprises:

  1. a gene name, genomic coordinates or a pasted sequence (including RefSeq and ENSEMBL gene IDs),
  2. a growing list of organisms,
  3. the choice between CRISPR/Cas9, CRISPR/Cas9 Nickase, CRISPR/Cpf1 or TALEN mode.

The advanced options provide the user with more flexibility when choosing target sites.

If you use our tool please cite:

Kornel Labun; Tessa G. Montague; James A. Gagnon; Summer B. Thyme; Eivind Valen. (2016). CHOPCHOP v2: a web tool for the next generation of CRISPR genome engineering. Nucleic Acids Research; doi:10.1093/nar/gkw398


Tessa G. Montague; Jose M. Cruz; James A. Gagnon; George M. Church; Eivind Valen. (2014). CHOPCHOP: a CRISPR/Cas9 and TALEN web tool for genome editing. Nucleic Acids Res. 42. W401-W407

This work was supported by a National Defense Science and Engineering Graduate (NDSEG) Fellowship; the American Cancer Society; the Human Frontier Science Program and the National Human Genome Research Institute (NHGRI) Center for Excellence in Genomics Science.

CHOPCHOP is for non-profit and academic use only. All commercial rights are reserved.