Protospacer Workbench - an offline software for for rapid sgRNA design and off-target prediction

An offline tool available for MacOS X system is now available for free at http://www.protospacer.com/. The software combines the advantages of various CRISPR design algorithms. It features single or paired target design of gRNAs for which cleavage efficiency is estimated based on the Doenech score and off-target sites are predicted and validated. The software can handle very large genomes, custom sequences or user defined genes. gRNA design is only available for S. pyogenes Cas9 for N(20)NGG sites. It has a graphical user interface and does not require programming skills.  The workbench also connects to the IGV viewer.
Source: http://www.nature.com/nbt/journal/vaop/ncurrent/full/nbt.3291.html