We are using uWS for our platform which is completely written in native C++.<p>I haven't tested the scalability to a million clients, but I have no reason to doubt it could handle it.<p>On the other hand, I <i>have</i> tested with 20k clients each sending 100 x 128 byte messages a second.<p>So I've tried pumping 2 million messages a second through our platform (which is at the envelope of my expected load), and the server just sits there and takes it. At these levels saturating the network interface is the main issue.<p>I've also tried it in single core, 4 core, 8 core and 20 core threaded configurations. Everything works as it should and contention is quite minimal.<p>The ability to achieve that over WebSockets is largely due to the work Alex has done (and continues to do) to squeeze every last ounce out of the stack.<p>As far as I'm concerned uWebSockets 0.10.0 is rock solid and at the point where using it in production is totally fine.<p>I can totally recommend it.<p>Congrats on the release Alex and thanks for the lib!