Is Discord Running?

...

var ws = new WebSocket('ws://127.0.0.1:6463')

ws.addEventListener('open', function(e) {
  // YES
})

ws.addEventListener('error', function(e) {
  // NO
})

The Discord client exposes a local RPC server on port 6463.

This allows a website to use the WebSocket API to detect which visitors have the Discord client running - or not.

This short post was inspired by "Why is This Website Port Scanning me?" - a blog post that calls out websites that port-scan their visitors for fingerprinting purposes.