Agent is an open source tool for fast genome-wide association studies (GWAS) using the agent file format from "Compression for population genetic data through finite-state entropy" (W. Chen and L. T. Elliott, 2021, biorxiv preprint 10.1101/2021.02.17.431713v2). This tool can convert files to the agent format and perform univariate GWAS. The website hosting the documentation including example data file downloads, version history, build instructions, manual with usage examples, and license is at agent.engineering.