Multilingual websites allow companies to reach business partners and customers all over the world. Localization defines the process of adopting a source website linguistically and culturally to its target locales. This process is needed every time content in the source website is created or changed and therefore requires a full-cycle localization process to capture differences between the various locales accurately. We propose the Delta Model as a framework to facilitate and automate multilingual website maintenance and its localization. A multilingual document structure (MDOM) is introduced to extends the hierarchical structure of the regular document object model (DOM) in order to determine localization and non-localization sensitive content. We show that MDOM as a valuable notation for both change representation as well as necessary localization operations within frequently changed content and illustrate the usefulness of this framework based on real-world examples.