Yes, Cloudflare supports ASP.NET SignalR.
SignalR negotiates what transport method to use: long polling or WebSockets.
Customers using Cloudflare Railgun should note that when SignalIR negotiates using:
- WebSockets, Railgun is bypassed.
- Long polling, the request goes over Railgun but, if such request is idle for 60 seconds, Railgun times out and returns a 527 error.
Read more about Cloudflare's support of WebSockets.