Explore the journey of transitioning from legacy in-house software to robust open-source solutions in this insightful PyCon US talk. Discover the challenges of dealing with outdated code and learn why Python has become a popular choice for open-source projects. Gain valuable insights into navigating the open-source landscape, implementing best practices, and leveraging Python's advantages in software migrations. Follow a three-phase approach to evaluating and integrating open-source tools, using Apache Airflow as a case study. Understand the benefits of writing production-quality code quickly, customizing configurations, and seamlessly integrating with existing systems. Learn how to overcome common pitfalls, debug effectively, and utilize Python's flexibility for data reconciliation and memory profiling. Whether you're a seasoned developer or new to open-source, this talk provides practical knowledge for modernizing your tech stack and improving your software engineering skills.