Google Search console https://support.google.com/webmasters/answer/6229325?hl=en-IN https://search.google.com/search-console/welcome real-time web via firebase: How firebase live database listeners work How Websockets work Push Technologies Google(GCM/FCM), Apple(PNS) Real-time web https://en.wikipedia.org/wiki/Google_Cloud_Messaging#Technical_details