All modern browsers support HTTP/2: https://caniuse.com/#feat=http2 https://caniuse.com/#feat=http2 HTTP/2 server push was originally intended as a pre-caching

All modern browsers support HTTP/2: https://caniuse.com/#feat=http2 https://caniuse.com/#feat=http2 HTTP/2 server push was originally intended as a pre-caching mechanism (send resources in advance to the client, in case they might get asked for), rather than for pushing data spontaneously (aka in realtime). As far as I know, browsers don't yet have a way to notify the application if a resource has been pre-cached, or offer a way for applications to hijack the push handler to avoid caching. So, for now, WebSockets (with or without Socket.io) or HTTP Server-Sent Events are more appropriate for realtime apps than HTTP/2 server push. Note that you can send an SSE stream within HTTP/2. That said, the Web Push protocol (https://tools.ietf.org/html/rfc8030 https://tools.ietf.org/html/rfc8030) specifies the use of HTTP/2 server push for delivering data in realtime. So this could become a more common thing in the future.