Since Google Chrome dropped the NPAPI support, this extension is required to get the functionality previously available via Jazz-Plugin. This extension requires Jazz-Plugin v.1.5 or later. Please compare MIDI functionality in Chrome with and without the extension: https://jazz-soft.github.io/modules/jzz-webmidi.html (plain WebMIDI API) https://jazz-soft.github.io/modules/jzz-crx.html (Jazz-MIDI extension) Developers: use JZZ.js for the best cross-browser compatibility. https://jazz-soft.net/doc/JZZ Please visit https://github.com/jazz-soft/jazz-midi to view the source code and leave your feedback.