draw.io - Online diagramming application
Elasticode - Build, deploy & personalize native mobile experience
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.
Snackwyze - Clickable walkthroughs from screen recordings in seconds
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Cohere - A powerful way to visually demonstrate ideas and connect ideas together