draw.io - Online diagramming application
WordPress - WordPress is web software you can use to create a beautiful website or blog. We like to say that WordPress is both free and priceless at the same time.
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.
Pendo - Pendo helps product teams understand and guide users to create product experiences that customers love.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Gotcha - User-centric analytics & triggers, driven by micro-surveys