I believe webkit, and by extension, node-webkit, can run asm.js code since it is just a subset of JavaScript, but it currently doesn't understand the type hinting in asm.js to enable the code to run any faster than vanilla JavaScript. AFAIK, Firefox is currently the only browser that can optimize running asm.js code to see any speed benefits. I have not used asm.js; this based on what I've read, so I could be totally wrong.