As developers, we often encounter scenarios where traditional serverless functions fall short — think workflows that require pausing for days or months, waiting for external events like user approvals or API callbacks. Enter AWS Lambda Durable Functions, a feature unveiled at re:Invent 2025, designed to bring durable execution patterns directly into Lambda. This allows you to craft stateful, resilient applications using familiar languages like Python or JavaScript, with the AWS SDK handling state management, retries, and orchestration. Perfect for e-commerce order processing, AI model training pipelines, or enterprise approval systems, Durable Functions eliminate the need for complex workarounds like external queues or databases.

In this detailed guide, this article will walk through learning and implementing AWS Lambda Durable Functions step by step, complete with code snippets, diagram explanations for visualization, and a comprehensive comparison with other durable execution engines like Azure Durable Functions, AWS Step Functions, and Temporal.