Anima App - Design, get feedback, convert to code, publish, iterate.
draw.io - Online diagramming application
Timeline for Sketch - Create beautiful timeline animations in Sketch
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.
BuilderX - Design to code, designers and developers on one platform.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.