Railgun is used between CDN and http server, while this one seems to be between browser and http server. Railgun only requires website to deploy a client, and

Railgun is used between CDN and http server, while this one seems to be between browser and http server. Railgun only requires website to deploy a client, and cooperate with cloudflare. User's client doesn't have to be Chrome or whatever; web server doesn't need to be aware of Railgun. It's transparent to both HTTP clients and HTTP servers. SDCH, however, requires a modification to HTTP/1.1 protocol, which implies changes in both HTTP clients and HTTP servers. Both are quite promising, though, Railgun is easier to adopt.