In the last decade, software has grown in complexity and size, while development timelines have diminished. As a result, component-based software engineering is becoming routine. Component-based software reliability assessment combines the architecture of the system with the reliability of the components to obtain the system reliability. This allows developers to produce a reliable system and testers to focus on the vulnerable areas.;This thesis discusses a tool developed to implement the methodology previously created for early reliability assessment of component-based systems. The tool, Early Component-based Reliability Assessment (ECRA), uses Rational Rose Unified Modeling Language (UML) diagrams to predict the reliability of component-based software. ECRA provides the user with an easy interface to annotate the UML diagrams and uses a Bayesian algorithm to predict the system reliability. This thesis presents the methodology of ECRA, the steps taken to develop it, and its applications
