The VGF mobility SmartApp for public transport in Frankfurt, Germany, is a mobile web app developed with Sencha Touch for iPhone and Android smartphones. The app allows you to search for nearby barrier free stations, informs the user of delays, and displays Twitter news. In this session, we will go through the app architecture, show how large data lists from a Ruby on Rails backend are loaded and handled, and how custom templates, Google Maps and Twitter were integrated. Finally, we cover the custom SASS theming, including custom CSS3 elements - and discuss the lessons we learned and the performance optimizations we used during development. Nils Dehl is 28-year-old senior developer living in Darmstadt Germany, working for dkd Internet Service GmbH, an owner-managed full-service internet agency specialized in TYPO3 in Frankfurt Germany. Nils has worked in ExtJS application development since version 2.x, and Sencha Touch since its beginning. Besides development, he also holds training and conference talks for both products and is the organizer of the ExtJS/Sencha Touch meetup in Frankfurt. In his spare time he plays table-tennis and squash, likes to travel, read and ski and of course photography. Nils is the official ‘unofficial’ Sencha conference photographer!