Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for performing client-side click tracking. In one aspect, a method includes receiving, by a client, a resource from one or more servers. The resource includes (i) a link, (ii) click tracking code, and (iii) local storage monitoring code. The method includes invoking, by the client, the click tracking code and the local storage monitoring code, detecting, by the invoked click tracking code, a selection of the link, and generating, by the invoked click tracking code, a representation of the selection. The method includes storing, by the invoked click tracking code, the representation of the selection in a local storage on the client, determining, by the invoked local storage monitoring code, to communicate the representation of the selection; and communicating, by the invoked local storage monitoring code, the representation of the selection to the one or more servers.