draw.io - Online diagramming application
Sketch - Professional digital design for Mac.
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.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Adobe Illustrator - Adobe Illustrator is a vector graphics editor.