I believe they use the Chromium Embedded Framework. It has been discussed on Quora [1] by some Spotify Devs. [1] https://www.quora.com/How-is-JavaScript-used-

I believe they use the Chromium Embedded Framework. It has been discussed on Quora [1] by some Spotify Devs. [1] https://www.quora.com/How-is-JavaScript-used-within-the-Spotify-desktop-application-Is-it-packaged-up-and-run-locally-only-retrieving-the-assets-as-and-when-needed-What-JavaScript-VM-is-used https://www.quora.com/How-is-JavaScript-used-within-the-Spot...