When cloud application developers are working with docker-compose to combine multiple microservices into a single manageable entity, they can make some easy mistakes. To prevent these mistakes, they can rely on internal validation logic, which however does not catch many of the typical issues. Therefore, researchers at the Service Prototyping Lab at Zurich University of Applied Sciences wrote a dedicated quality check and assessment tool targeting developers, but also students trying to learn the technology, which has a wider range of checks. The DCValidator tool is available as a web application (see demo instance) or command-line interface. This blog post describes how to check that docker-compose files are free of issues.