CHOPCHOP is a web tool for identifying CRISPR–Cas single guide RNA (sgRNA) targets. Just select your target gene, sequence or chromosome coordinates, your organism and the desired CRISPR mode and find matching target sites! CHOPCHOP incorporates the latest Cas9, Cpf1 and TALEN findings into CHOPCHOP’s algorithm for scoring and ranking potential target sites. Select between default and advanced options to tailor your experience after needs and experience, directly in the website. This tool is managed by ELIXIR Norway.