Systems and methods of site traffic control are disclosed. In some example embodiments, a request for an online service to perform an operation is received from a user on a client device, and at least one overload condition for the online service is detected, or otherwise determined, with the overload condition(s) corresponding to a request time of the request. A standard of restriction is selected from a plurality of standards of restriction based on the overload condition(s), and the selected standard of restriction is used as a basis for either denying or permitting the user access to the operation of the online service.