Cortex is freely available under the GPLv3 license. However we do ask that if you use Cortex and it leads to a publication, that you reference our first paper: "De novo assembly and genotyping of variants using colored de Bruijn graphs", Iqbal(*), Caccamo(*), Turner, Flicek, McVean (Nature Genetics) (2012) (doi:10.1038/ng.1028)