The K-mer File Format: a standardized and compact disk representation of sets of k-mers

Bioinformatics applications increasingly rely on ad hoc disk storage of k-mer sets, e.g. for de Bruijn graphs or alignment indexes. Here, we introduce the K-mer File Format as a general lossless framework for storing and manipulating k-mer sets, realizing space savings of 3-5x compared to other formats, and bringing interoperability across tools.