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.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
draw.io - Online diagramming application
Sketch - Professional digital design for Mac.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Invision - Prototyping and collaboration for design teams