CS50.dev is a cloud-based programming environment offered to students taking CS50 or CS courses at Harvard University, on-campus or online. Integrated with GitHub Codespaces, CS50.dev simplifies the initial challenges commonly faced by students and instructors due to the complexities involved in setting up programming environments at term’s start. This demo offers an in-depth exploration of CS50.dev’s architecture and presents a detailed guide on customizing Docker images and Devcontainers to meet the specific needs of various courses within GitHub Codespaces. The demo will also provide general guidance on how to help students transition from CS50.dev to using VS Code independently on their local machines at the term’s end.