Methods, systems, and apparatus, including computer programs encoded on computer storage media, for data aggregation. The methods, systems, and apparatus include determining whether a site-specific script for extracting financial data from a particular financial institution website is available; in response to determining that a site-specific script for extracting financial data from the particular financial institution website is not available, generating a site map of web pages and web page segments in the financial institution website, wherein the site map is generated based on at least in part on a statistical analysis of web pages and web page segments that are not in the financial institution website; generating, based on the site map of the financial institution website, a site-specific script for extracting financial data from the financial institution website; and extracting, for one or more users, financial data from the particular financial institution website using the generated site-specific script.