QGIS - QGIS is a desktop geographic information system, or GIS.
draw.io - Online diagramming application
GeoServer - The reference implementation of the Open Geospatial Consortiums WFS and WMS services, GeoServer is...
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
ArcGIS - ArcGIS software is a data analysis, cloud-based mapping platform that allows users to customize maps and see real-time data ranging from logistics support to overall mapping analysis.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.