The evolution of Web technologies leads to software premature obsolescence requiring technology-independent representations to increase the reuse rates during the development process. They also require integration into service-oriented architectures to exchange information with different Web systems supporting runtime interoperability. Web Applications (WebApps) run on devices with different capabilities and limitations increasing the complexity of the development process. To address these challenges, different proposals have emerged to facilitate the development of WebApps, which is still an open research field with many challenges to address. This paper presents a model transformation architecture based on software standards to automatically generate full stack multi-layered WebApps covering Persistence, Service, and Presentation layers. This transformation architecture also generates the set of test cases to test WebApp business logic. The proposed transformation architecture only requires a UML platform-independent class model as an input to generate fully functional Web applications in a three-tier architecture including the three layers, while most proposals focus on the generation of the Presentation layer. In addition, this architecture employs software industry standards to enable an easy integration into third-party tools and development environments. The transformation Architecture proposed has been empirically validated on the case study of a fully functional travel management WebApp that is generated using a UML class diagram employing a third-party tool integrated into the same integrated development environment.