1. A method comprising: at a content personalization system, identifying a hash value based on a communication received from a third party web server; identifying, based on the hash value, a member identifier associated with a visitor to a web site associated with the third party web server, the member identifier identifying a particular member of a social networking service; accessing member data associated with the member identifier in a record of a database associated with the social networking service, the member data including attribute data that is associated with one or more members of the social networking service, the attribute data being represented as name-value pairs; identifying, using one or more hardware processors, one or more attributes associated with the particular member based on one or more name-value pairs representing the one or more attributes associated with the particular member in the member data; selecting, at a content personalization system, an item of content for presentation to the particular member, the selecting being based on the one or more attributes associated with the particular member; generating, at the content personalization system, a widget for inclusion in the web site associated with the third party web server; and causing, by the content personalization system, inclusion of the widget in the web site at a time of display of the web site in a browser of the client device associated with the particular member, the inclusion of the widget improving the web site based on presenting the item of content in a user interface of the widget included in the web site.