Open source GIS

Open source GIS is geographic software whose source code is published under a licence that lets anyone use, inspect, change and redistribute it. The best known examples are QGIS on the desktop, PostGIS as a spatial database, and a large ecosystem of libraries that most geospatial software, open or not, is built on.

For public sector work the argument is usually not price. It is that the method is inspectable and the result is reproducible. If a planning decision rests on an analysis, anyone can see how the analysis was calculated, and the municipality is not dependent on one vendor continuing to support one product. Data and workflows stay portable.

GOAT is open source and built with open source software, so the same applies to the accessibility methods it implements. The code is available to read, which means the numbers it produces can be checked rather than trusted.