I have started working on socket.io. As i'm new to socket.io so i don't know much about it. can anyone tell me whether node is must for socket.io or not ? can we use socket.io as standalone without node or express ?
You cannot use socket.io as standalone. But you can use it in Languages other than nodeJS like Eelco said.
socket.io can be used in: Erlang, Android, Java, Lua, Objective-C, C, C++, QT QML, Perl, Go, Python, Ruby, Flash, Haxe, PHP, .NET, C++/Win32and unity3d.