Thanks to the advent of almost ubiquitous mobile internet and fueled by thousands of add-on applications, smartphones enjoy an increasing popularity. Companies who want to reach their customers with mobile devices need to consider implementing their solutions for an ever increasing plethora of devices and platforms. Given the costs for multi-platform development, the million-dollar question is, can we build multi-platform applications which address the individual characteristics of the respective platforms without sacrificing stability and slick UIs? In this talk, we will explain how we built APPLause, a DSL for mobile apps, using model-driven approaches to enable us to target multiple platforms at once. We will show how we developed the language along the concepts of the supported platforms, while at the same time making sure the generated application can be extended manually where needed. The DSL we describe has been used to build the conference app for ESE (available for iPhone and Android) and is available as open source.