Web tools > VBA-WebSocket
Microsoft example code for a WebSocket client which can be used in conjunction with an echo server. There is also a class and an async version built by the discoverer of the microsoft code.
vba-websocket
VBA Websocket Sample (Echo Server Client)
While searching for examples of VBA code that use the Websocket protocol, I found the original Microsoft example code for an echo server client (copy in WinHttpWebSocketSample.bas).
The files for "Main.bas" and "WinHttpCommon.bas" can be imported into VBA to make a client that works with an echo server.
Unfortunately, https://websocket.org/ is no longer working, now using ws://ws.vi-server.org from: github.com/vi/wsmirror