That's sort of what https://flowchart.fun https://flowchart.fun is. Although, it doesn't have as many graph types as PlantUML. Mermaid also has https://mermaid.

That's sort of what https://flowchart.fun https://flowchart.fun is. Although, it doesn't have as many graph types as PlantUML. Mermaid also has https://mermaid.live/ https://mermaid.live/ running in the browser.