Durable execution refers to the ability of a program to persist its execution state, allowing it to recover from crashes, interruptions, or restarts and continue from where it left off. Traditionally, durable execution is achieved through external workflow orchestration, which involves an orchestrator and workers that manage the control flow, persist outputs, and resume processes, but this approach can be cumbersome and complex. To simplify this, DBOS Transact offers a lightweight, open-source library that implements durable execution directly within a program, using Python decorators to manage execution states and persist them in a Postgres database. This allows workflows to resume from the last completed step upon a program restart, provided the workflows are deterministic. Additionally, the library supports features like durable sleep, messaging, and queues, providing a robust foundation for building reliable and stateful applications.