LEFT is a web-based decision support tool to help industry evaluate patterns of relative ecological value across a landscape to inform land use planning and minimize environmental impact. Users choose an area of interest from a global web-based map and receive a series of high-quality datasets using standard published algorithms to produce maps at 30m resolution of land cover class, numbers of globally threatened terrestrial vertebrate and plant species, beta-diversity of terrestrial vertebrates and plants, habitat intactness, habitat connectivity, and vegetation resilience. LEFT also generates an aggregated map of relative ecological values, a customised PDF and ZIP file of GIS data for the area requested. The tool is designed to be highly intuitive, and requires no special software or expertise: novice users can receive an informative analysis in minutes. LEFT is intended as a pre-planning tool to complement but not replace the process of detailed environmental impact assessment.