Codename One

An open-source mobile-first toolkit for building high-quality, cross-platform native apps for Android, iOS, Desktop & Web. Rapid cross-platform app development using Java or Kotlin with 100% code reuse. Apps are compiled down to native code for maximum performance and a smooth user experience. Write, debug, and test apps all inside your IDE (IntelliJ, Eclipse, VSCode or NetBeans) using the Codename One simulator. One-click for app-store-ready device builds, without the headache of maintaining native SDKs. Build beautiful UI with Codename One’s rich set of widgets, specifically designed for mobile apps. Native look and feel out of the box, but fully themeable using CSS to provide your own unique look. Compiles Java or Kotlin into native code for iOS, UWP (Universal Windows Platform), Android and even JavaScript (with seamless PWA and Thread support) Changes you make in your Java/Kotlin source code will be applied immediately to your already-running app in the simulator.