Comment by thangalin
While Mermaid gets the limelight, Kroki[1] offers: BlockDiag, BPMN, Bytefield, SeqDiag, ActDiag, NwDiag, PacketDiag, RackDiag, C4 with PlantUML, D2, DBML, Ditaa, Erd, Excalidraw, GraphViz, Nomnoml, Pikchr, PlantUML, Structurizr, Svgbob, Symbolator, TikZ, Vega, Vega-Lite, WaveDrom, WireViz, and Mermaid.
My Markdown editor, KeenWrite[2], integrates Kroki as a service. This means whenever a new text-based diagram format is offered by Kroki, it is available to KeenWrite, dynamically. The tutorial[3] shows how it works. (Aside, variables within diagrams are also possible, shown at the end.)
Note that Mermaid diagrams cannot be rendered by most libraries[4] due to its inclusion of <foreignObject>, which is browser-dependent.
[1]: https://kroki.io/
Comparing MermaidJS with Kroki is a bit like comparing PDF.js to Adobe Acrobat. I don't think either is better than the other, they're just for different use-cases.
With MermaidJS, converting a diagram inside a web page requires adding a handful of lines to a HTML page. The execution is fast and local.
Kroki is a web-service. To use it in a web page means adding a dependency to an external provider (a free service exists, but asks for fundings). An alternative is self-hosting by running a Kroki container.
A few years ago, I added Mermaid diagrams to a project in a few minutes of work. Had we needed a much more complex tool, maybe I would have gone with Kroki, but not by myself; it would have required a change in the deploying process of the project.