Efflux (since 2016!) has been a music making solution that functions without requiring any additional software in your browser.
Efflux is packed with features and provides a lot of fine-grained control due to the tracker style sequencer. However, this also makes the learning curve steep.
To get around this, Efflux is now enriched with "Jam" mode, which basically allows you to play the synthesis engine live, where you can tweak the effects parameters, draw waveforms, record samples and connect WebMIDI to your hearts desire.
