I reached the same conclusion after comparing diagram-as-code tools — D2 feels cleaner and more expressive than Mermaid.
I’ve been working on an AI diagramming tool built around D2: https://aidiagrammaker.com/
You describe a system in plain English, and it generates architecture diagrams, flowcharts, and sequence diagrams in D2.
Edits can be made either directly in the D2 code or via a context-aware editor.
d2 produces real svgs but I've found them to have a hard time displaying in other svg editors. The d2 folks talk about that somewhere and they have some fixes for it.
Oh, finally, something that supports actual hierarchical state diagrams (that isn't Graphviz, no offense)... Mermaid's "You cannot define transitions between internal states belonging to different composite states" [1] has driven me up a wall for years.
The language is richer and all diagram types are implemented consistently in the same language in a way that can be composed, as opposed to being a collection of unrelated DSLs.
The improved visual appearance is clear from inspecting example diagrams, I believe.
I’ve been working on an AI diagramming tool built around D2: https://aidiagrammaker.com/ You describe a system in plain English, and it generates architecture diagrams, flowcharts, and sequence diagrams in D2.
Edits can be made either directly in the D2 code or via a context-aware editor.