[justasitsounds]

plantUML[0] may be what you're looking for, specifically the activity diagrams[1].I've been using it extensively for sequence diagrams (has more features than websequencediagrams.com). Most recently I've been using this C4 architecture diagrams extension[2]. There's a VSCode preview extension[3] and a docker image[4] for running a plantUML server locally that lets me create and share version controlled diagrams with my colleagues easily.

I especially like that there's an ascii renderer for the sequence diagrams that makes embedding them in Readme's very easy

[0] http://plantuml.com/ [1] http://plantuml.com/activity-diagram-beta [2] https://github.com/RicardoNiepel/C4-PlantUML [3] https://marketplace.visualstudio.com/items?itemName=jebbs.pl... [4] https://hub.docker.com/r/plantuml/plantuml-server/