PropRatt is a property-based testing framework for testing Async Rattus programs. The key component of PropRatt is its specification language, which extends basic linear temporal logic with a means to express properties of several concurrent signals. This allows users to express temporal properties that relate data coming from different signals at different points in time. More details about the specification language can be found in the accompanying paper. Example specifications written in PropRatt: Specification for a simple GUI application Specification for basic signal combinators (map, zip, scan, etc.)