Web based step sequencer / piano roll for sequencing rnbo synths in a web page?

Hey,
What I'm asking is a bit out of the scope of this forum strictly speaking as it is more about web development than Max, but I assume some of you here might have some answers.

I would like a step sequencer (or a piano roll) that I can put into a web page in order to control an embedded rnbo synth.

My dream goal is something like [live.step], or what we can see in the learningmusic.ableton.com playground. The latter is based on "SimplePianoRoll.js" that can be declined in various flavors. However it seems to be custom made and I don't feel like I want/have the right to de-obfuscate / reverse engineer that code to use it for my own purpose.

I found a few js piano roll examples in github but they're ugly and either over simplified or too complicated and I feel like it would be faster to start making mine from scratch.

Did anyone of you already tackled this problem?

Do you think of any js example or api that has a piano roll to work with?