I've downloaded vcvrack, but not actually tried it out yet. It looks awesome. However, the project I'm working on is a web-based synth using the HTML5 Web Audio API. It's built using Tone.js and NexusUI.js, so vcvrack isn't really applicable, as far as I can tell at least!

Thanks for the recommendation though. :)

I was going to recommend VCV Rack as well :-)