A cloud platform records a wealth of information regarding program execution. Most cloud service providers offer dashboard monitoring tools that visualize resource usage and billing information, and support debugging. In this paper, we present a tool that visualizes cloud execution logs for a different goal-To facilitate program understanding and generate documentations for an application using runtime data. Our tool introduces a new timeline visualization, a new method and user interface to summarize multiple JSON objects and present the result, and interaction techniques that facilitate navigating among functions. Together, these features explain a serverless cloud application's composition, performance, dataflow and data schema. We report some initial user feedback from several expert developers that were involved in the tool's design and development process.