BXML is an XML-based markup language for simplifying the construction of Java object hierarchies.

While BXML is most often used to define the user interface of an Apache Pivot application, it is not limited to user interface construction, and can actually be used to create hierarchies of any object type. In the case of Apache Pivot the designer can place the WTK-components and set their properties without writing a single line of Java code. In more complex projects there usually is one class file for each BXML file to hold the logic, though there are other possibilities.