Seaside is a free and open source web application framework for developing web applications in Smalltalk.

Seaside provides a component architecture in which web pages are built as trees of individual, stateful components, each encapsulating a small portion of a page. Seaside uses continuations to model multiple independent flows between different components.^[1] Seaside is a continuation-based web application framework^[2] based on the ability to manipulate the execution stack of some implementations of Smalltalk.