Communicating information between applications executing on a client device via authentication information generated by an application

A computer program product comprising a non-transitory computer readable storage medium having instructions encoded therein on that, when executed by a processor included in a client device, cause the processor to:

• identify an additional application executing on the client device, the additional application associated with an application executing on the client device associated with a user, the additional application different from the application;
• determine the identified application is installed on the client device;
• receive a request for the application and the additional application to exchange information, the request identifying the additional application and a user identifier associated with the user by the application;
• responsive to receiving the request for the application and the additional application to exchange information, communicate a request for authentication information to access an online system associated with the application to the online system associated with the application, the request for authentication information identifying the additional application and identifying the user of the application via the user identifier associated with the user by the application;
• receive the authentication information generated by the online system from the online system associated with the application after the online system stores an association between the authentication information and the user identified associated with the user by the application;
• launch the additional application and communicate the authentication information to the additional application;
• and
• communicate a request to verify the authentication information from the additional application to the online system associated with the application, the request to verify the authentication information including an additional identifier associated with the user by the additional application, wherein the online system stores an association between the additional identifier associated with the user by the additional application and the user identifier associated with the user by the application at the online system in response to the online system verifying the authentication information from the additional application.