pikchr is awesome. A project I did recently was a WASM-compiled pikchr library to generate diagrams directly
in the browser [1]. Here's a very early demo of a live editor you can play around with [2].
Not fully-featured yet but what I'd like to eventually do is set it up in a similar way to the mermaidjs editor [3]. They encode the entire diagram in the url. That makes it really easy to link to from markdown documents and has the nice benefit that the diagram is immutable for a given url so you don't need a backend to store anything.
[1]: https://www.npmjs.com/package/pikchr-js