Pendo - Pendo helps product teams understand and guide users to create product experiences that customers love.
draw.io - Online diagramming application
Tutorialize - Tutorialize allows website owners to create rich on-screen website tutorials that guide their users around their site.
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.
JourneyFlow - JourneyFlow is an app designed to help marketers and customer experience managers develop and visualize customer journeys.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.