get https://api.kongregate.com/api/authenticate.json
Verifies a user's identity
The Authentication API allows Kongregate players to play any game without registering or entering a password. By making a call to the web service from your game server you can securely determine the player's Kongregate user id and username.
Note
This method should only be called from a server, not a game client.
For more information on how Kongregate users should be authenticated in your game, see this document.