Abstract: Plug-in frameworks support the development of component-based software that is extensible and customizable to the needs of specific users. However, most current frameworks are targeting single-user rich client applications but do not support plug-in-based web applications which can be extended by end users. We show how an existing plug-in framework (Plux.NET) can be enabled to support multi-user plug-in-based web applications which are dynamically extensible by end users through server-side and client-side extensions.