draw.io - Online diagramming application
Plant - Version control app and plugin for 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.
Abstract - A secure, version-controlled hub for your design files
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Folio for Mac - Simple version control app for designers