code: an OAuth Code which can be exchanged for a valid user access token via a subsequent server-side request algorithm: A JSON string containing the mechanism used to sign the request, normally: HMAC-SHA256. issued_at: A JSON number containing the Unix timestamp when the request was signed. user_id: A JSON string containing the User ID of the current user. user: A JSON object containing the locale string, country string and the age object (containing the min and max number range of the age) for the current user. oauth_token: A JSON string that can be used when making requests to the Graph API. This is also known as a user access token. expires: A JSON number containing the Unix timestamp when the oauth_token expires. app_data: A JSON string containing the content of the app_data query string parameter which may be passed if the app is being loaded within a Page Tab. page: A JSON object containing the page id string, the liked boolean (set to true if the user has liked the page, false if not) and the admin boolean (set to true if the user is an admin of the page, false if they are not). This field is only present if your app is being loaded within a Page Tab. Below is the code for seeing whether or not a page is liked, grabbing the app_data, and redirecting based on those two variables.