1. A method, implemented by a first computing system programmed to perform the following, comprising: analyzing installation behavior of an application operating in a social networking service and generating an installation metric, wherein the social networking service comprises an online platform, wherein the installation metric is based on at least one of a setting change or a permission change, made by the application to a user profile space, during installation of the application; analyzing application activity of the application and generating an application metric, wherein analyzing the application activity of the application comprises: determining a purpose of the application based on a description of the application; and assessing whether the activity of the application exceeds the purpose of the application; analyzing permissions requested by the application and generating a permissions metric, wherein the permissions metric is based on at least one of the following permissions: accessing a user's social networking service friend list, posting on a friend's social networking service wall without user consent, messaging to all user social networking service contacts without user consent, or requesting social networking service chat permissions; and generating a reputation score of the application based on the installation metric, application metric, and permissions metric.