What is the best tool for architecture diagrams?
For communication, whatever your team already uses. For accuracy, the deciding property is not the tool but whether the diagram is connected to the code: versioned alongside it and checkable against it. A beautiful diagram in a disconnected design tool decays exactly as fast as an ugly one.
From Architecture diagrams that stay true, published 9 August 2026. That article is where the reasoning behind this answer is set out, including what it does not cover.