Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for on-demand scan engine deployment. In one aspect, a method includes obtaining parameters of a scheduled scan, the parameters defining computer assets to be scanned and performance requirements. The method includes obtaining historical data describing prior scans that were performed according to similar parameters. The method includes determining performance measures of the prior scans using the historical data. The method includes calculating resource requirements based on the parameters and the performance measures, the resource requirements being requirements that are determined to be needed to meet the performance requirements of the scheduled scan. The method includes determining a number of scan engines required to meet the performance requirements based on the resource scan requirements.