GeoServer - The reference implementation of the Open Geospatial Consortiums WFS and WMS services, GeoServer is...
QGIS - QGIS is a desktop geographic information system, or GIS.
Mapserver - MapServer is an Open Source platform for publishing spatial data and interactive mapping...
GRASS GIS - GRASS GIS is a free Geographic Information System (GIS) software used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization.
ESRI Geoportal Server - Esri Geoportal Server is a free, open source product that enables discovery and use of geospatial resources including datasets, rasters & Web services.
SAGA GIS - SAGA - System for Automated Geoscientific Analyses - is a Geographic Information System (GIS)...