Snappa - The perfect graphic design tool for digital marketers.
draw.io - Online diagramming application
Canva - Canva is a graphic-design platform with a drag-and-drop interface to create print or visual content while providing templates, images, and fonts. Canva makes graphic design more straightforward and accessible regardless of skill level.
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.
Artboard Studio - Online graphic design app mainly focused on product mockups.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.