Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
draw.io - Online diagramming application
GIMP - GIMP is a multiplatform photo manipulation tool.
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.
Affinity Photo - Affinity is the imaging and design suite for creative professionals exclusively for Mac.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.