In this session you will learn all aspects for application development with Qt: we will present development, testing and deployment tips and best practices used in the Qt World Summit conference app and other apps with millions of downloads. We explain the code used in such applications and present code snippets so you can develop these applications yourself. This session shows how to develop applications for multiple screen sizes, screen resolutions and form factors like smartphones, tablets, desktop PCs and embedded devices with Qt. We show how you can use the same code base, while having native-looking UIs & UX across platforms. This includes tips for responsive design with Qt and how to best leverage the screen size, resolutions and screen densities. We also answers questions like: • What are best practices for user authentication? • How to connect to a REST API? • Which backend shall I use in my application? • How to synchronize data from the backend with the client and how to cache it for offline usage? • How to use multiple languages and internationalization? • Tips and tricks for List Views You will also learn how you can test multiple screen resolutions and platforms including iOS & Android and their native UI from a single Desktop application. In the second part of this session, we will highlight how you can leverage the full app lifecycle with Qt: from design to development, testing, deployment to publishing. And how you can efficiently perform post-publishing tasks like analytics & ongoing app improvements in the Qt ecosytem. This presentation gives you a technical overview with code snippets and hands-on examples of the possibilities with Qt for multi-screen development and multi-platform application development and shows best practices for an efficient app lifecycle with Qt.