Disclosed are various embodiments for generating network pages using customer-supplied page generation code. A network page request is obtained from a client. The network page is associated with a network site hosted by a hosting provider on behalf of a customer. Customer data is aggregated from multiple data sources. Customer-supplied page generation code is executed to generate the network page. The page generation code may access the customer data through predefined variables, but the page generation code is restricted from accessing the data sources directly. The network page is sent to the client in response to the request.