I like versions of this that are web components so that they're declarative and you can just drop them into HTML.

<shader-doodle> is one: https://github.com/halvves/shader-doodle but it hasn't been updated in a long time and I think builds to UMD

<shaderview> is a newer one with a nice site, but I haven't used it: https://keithclark.github.io/shaderview/