JavaFX Scene Builder is a visual layout aka WYSIWYG tool that allows users to quickly design JavaFX application user interfaces without coding. You can easily create great looking user interfaces with just drag and drop of components.
JavaFX Scene builder save the design as FXML format. These files can be directly loaded to the JavaFX programs. It is written in Java and is available in all major platforms. It provides nice options like ability to add embedded CSS, generate controller skeleton etc.
Watch the tutorial video: JavaFX scene builder tutorial for beginners.
Making Responsive GUI
Making GUI responsive is very important. Nowadays the device sizes varies from handheld to wall TVs. Using the right containers and component configurations, it is possible to quickly develop JavaFX GUI using scene builder.
Watch the tutorial on Making GUI responsive with Scene Builder.
Download Scene Builder
Current Gluon is maintaining JavaFX scene builder. You can download it for your platform from https://gluonhq.com/products/scene-builder/