Improved identification of a computer configured with an operating system (OS), a web browser and one or more applications is disclosed. An identifying code for advertisers (IFA) may be obtained via the operating system (OS) of the computer. A first application configuring the computer may include instructions to initiate an ad call comprising a request including the IFA to cause the first application to render an advertisement received by the computing device from a first web resource in response to the ad call. The web browser may execute the script to associate the web browser with a durable id (DID). The DID and the IFA may be correlated.