showFoto - ShowFoto is the standalone image editor of the digiKam project.
draw.io - Online diagramming application
PixBuilder - Free Photo Editing Software for PC
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.
PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.