Distributed systems testing presents unique challenges due to the difficulty in predicting how small failures can lead to large-scale errors across clusters. DataStax has developed Fallout, a large scale distributed testing tool that allows engineers to define and run experiments on running clusters in an automated and repeatable manner. Fallout integrates with NoSQLBench for simulating production workloads and is designed to work with existing testing tools and infrastructure. It uses Kubernetes for managing the Cassandra cluster lifecycle, allowing developers to focus on writing code and experiments. The tool is now available for download under the Apache License.