The Planets Testbed is an open access web application for the digital preservation community, providing an experimental framework for evaluating preservation tools and approaches in a controlled environment. The core technical architecture uses a scalable serviceoriented approach, through which preservation services can be accessed, exercised and orchestrated so that their effects and performance can be measured. The Testbed makes it easy to explore a wide range of preservation services, including many of the software products developed in the Planets project. The services, workflows and measurement processes are all highly automated, allowing large amounts of data to be collected via mass experimentation. These measurements are stored in a stable but extensible semantic structure, allowing the results to be shared with the wider community, across institutional and contextual boundaries. This knowledge base, and the available corpora of benchmark content, provides users of the Testbed ...