System and methods for asynchronous processing within a web page lifecycle, enabling web page developers to integrate asynchronous work within the web page implementation that can store state inside the page and is applied to requests to the particular page. Handlers initiate event-based or task-based asynchronous operations without keeping a dedicated thread while waiting for a response. The thread is returned to a pool of available threads upon initiation of the process. Results are received on other threads and provided to the page before rendering. Timeout errors are also provided, if a particular result is not received within specified period. The events are delivered in a serial manner so that the page developer uses request instance data without explicit synchronization. This makes a high-scale, asynchronous processing model less complex and more accessible to developers accustomed to web scripting, which is traditionally synchronous.