OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
jHipster - JHipster is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures.
BuildFire - BuildFire is the easiest way for small businesses to build a mobile app in a matter of minutes for iOS and Android.
Spring Framework - The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.