Free and Open Source GIS Tools for Format Conversion and Analysis
The problem with most “free GIS tools” roundup lists is that they treat GDAL, QGIS, GRASS, and PostGIS as competing products when they’re actually layers of the same stack. GDAL underpins QGIS. QGIS calls GRASS as a processing backend. PostGIS sits behind both for production data. Choosing between them isn’t “which is best” — it’s “which layer do I need to interact with directly.” This is a functional comparison: what each tool does well, where it breaks down, and which one to reach for when you receive a shapefile, a GeoJSON, or a KML and need it in something your software actually reads. ...