C4 is very interesting and I think tackles certain problems related to software architecture really well. It sort of turns the lower levels of an architecture,

C4 is very interesting and I think tackles certain problems related to software architecture really well. It sort of turns the lower levels of an architecture, which is mostly hardware and system software, into broad abstractions and focuses the effort on the stuff that sits above that in the stack. Which turns out to be surprisingly suitable for today's cloud-based/containerized scalable approaches. Related, Archimate is also very good and there's a lot of overlap, but grounds itself more into the infrastructure bits. I've used some version of diagram approaches similar to Archimate in the past to really great effect to deconflict systems and data sources and demonstrate how all the stuff we're buying and gluing together supports specific business and user workflow needs. Comments here about how this stuff all gets out of sync with the codebase are absolutely correct. But I've found that they can be excellent tools for use when you need to analyze a complex system or communicate systems and plans to a larger group. It's surprising how often there isn't really any form of cohesive documentation and just sitting down for a couple weeks and drawing boxes with lines connecting them can unblock and simplify failing and frustrated efforts to move forward, especially when teams are working in the same playpen. C4, Archimate, UML, whatever are really just good constrained diagramming languages you can use to capture specific things you wish to communicate, analyze, or memorialize. I think they aren't very good as preplanning and design tools. Many of us suffered from the big UML push days where every facet of a system down to class definitions were supposed to be laid out in excruciating detail by some chief architect's office before a line of code was laid down. Madness like "we'll just generate the code from the diagrams" caused millions to suffer. When coding actually did start, those thousands of hours of planning usually were just ignored and the developers just did what they wanted anyways.