Flask is much smaller, but there's so many things you can plug into it. I have written a number of things that you can add to Flask, which are all optional. So yes, I've written stuff to the web sockets in flask. That's actually the one that my most popular extension so that you can do a web socket and does it in a way that is very flask friendly. It has good sight on the bad side. The fact that the extension makes it simple doesn't mean that you do have request context which you don't when doing web sockets.