Amua is an open source modeling framework and probabilistic programming language. From the Swahili word for "decide"/"solve", Amua is designed to be:

• Transparent: The graphical user interface provides an intuitive way to develop and document models. As an open source framework, the underlying code is always available.
• Flexible: Models can be run in Amua or exported to other programming languages. This allows conceptual models to be separated from any particular implementation, making it easy to change model platforms.
• Accessible: Amua is free software and can be used as a teaching tool, or by researchers seeking an integrated modeling environment. The software is lightweight and can be used on any operating system with a Java Virtual Machine installed.
• Bayesian: As a probabilistic programming language, Amua allows model parameters to be treated as random variables and fit to data via model calibration using a variety of techniques.

Model types:

• Decision Trees
• Markov Models
• Discrete Event Simulation (planned)
• Microsimulation Models (multi-method) (planned)

You can get started here!