Thanks for linking to Archimate! I've been looking for similar software to build out attack trees when doing threat modeling.

I've been using these in the past [1] MonoDraw and this free [2] diagramming website. Came across [3] Draw today, although I have yet to try it.

[1] https://monodraw.helftone.com/ [2] https://www.websequencediagrams.com [3] https://www.draw.io/