Underwater acoustic modeling is used in many fields of research and development, which has resulted in a wide variety of acoustic models and applications, such as sensor performance prediction, sensor performance optimizations and acoustic impact on marine life. Many of the applications share a similar set of input parameters: bathymetry, sound velocity profile, environment, sediment type, etc. For ease of use, a Graphical User Interface (GUI) is usually created. To make a model or application accessible to a large user base and easy to use, good defaults need to be provided. Preferably, these defaults will be extracted from a global database to minimize user input, and thus potential input errors. Since many models share the same required input parameters, it makes sense to create a user interface framework to build acoustic modeling applications. TNO designed a framework to build GUI’s specifically designed for underwater applications. The framework has been named MUFASSA (Multipurpose Underwater Framework for APPROXA, SAKAMATA and SORIANT Assessments). This paper describes the components of MUFASSA and how to use them. TNO is looking for feedback and ideas to further improve the framework, and to apply it for more user interfaces implementing underwater acoustic models.