Besides the modules from the Redakt ecosystem, Redakt supports several other extensibility points. These are not replaceable modules, but you can insert another or your own implementation.
Redakt web rendering does not use the full MVC framework, but it does use the MVC view engine to render page layouts. By default, this is the Razor view engine. However, you can register any view engine in the service collection at startup, and Redakt will also use that view engine.