Understanding developers’ day-to-day behavior can help answer important research questions, but capturing that behavior at scale can be challenging, particularly when developers use many tools in concert to accomplish their task. In this paper, we describe our experience creating and using InSession, a system that integrates log data from dozens of development tools at Google. The system includes logs from not only the IDE, but also the tools that developers use to email, schedule meetings, ask and answer technical questions, find code examples, build and test their code, explore test and analysis results, and review each others’ code. We use these logs streams to create metrics and validate the accuracy of the metrics through agreement with diary studies. Finally, we show the impact of metrics derived from cross-tool logs by using them to evaluate the benefit of Google’s readability process; this evaluation shows readability is a cost-effective process for Google engineers and provides significant benefits to developer velocity.