Cloud computing has been on the rise for years and will not stop following this trend in the future. Developers must have an environment where they can design cloud applications and receive feedback on the Quality of Service their design provides. This thesis aims to provide a framework that calculates the availability of a software design based on a given reliability model. First, this work describes the essential principles needed to understand the model and the calculations. This includes scenarios, Message Sequence Charts, and Labelled Transition Systems. Then it describes the implementation of a scenario-based reliability model in detail. Additionally, I propose an algorithm that maximizes the availability value by recommending suitable services based on the availability model. The performance and precision of the implementation are then evaluated. We will see that the precision is accurate, and the number and density of transactions between cloud services influence the runtime the most. Finally, I summarize the found results and look at the future developments of the topic.