Hi HN, I'm Alex, at Terrastruct, where we've been making D2. This actually popped up on HN a couple months back, though it wasn't ready, e.g. not open source yet. It is now!

We also put up a site for you to compare D2 with MermaidJS, Graphviz, and PlantUML: https://text-to-diagram.com.

Full disclosure, we're a for-profit company. The open-core part is that we make an alternative layout engine which we sell (Jetbrains model, i.e. your copy is your's forever if you've paid for 12+ months). It's not packaged with D2, so you won't see it if you don't want it. D2 is perfectly usable without it, and integrates with multiple free open source layout engines (e.g. the one that Mermaid uses, "dagre", is D2's default). If you want to read more about our plans for D2: https://d2lang.com/tour/future.

Hope you can check it out! It's got an easy install (and uninstall) process.