Building APIs (and SDKs) that never break

Creating APIs and SDKs that don't break requires careful consideration of API versioning and understanding the complexities of how changes can affect users. APIs are essentially contracts, and breaking them can have significant consequences, especially when dealing with diverse and numerous clients who may rely on specific behaviors, even if unintentional. Versioning is critical, whether through explicit paths, headers, or other means, as it offers a structured way to manage changes without disrupting existing users. The challenge lies in balancing the need for innovation and improvements with the responsibility of maintaining backward compatibility. To mitigate potential breakages, strategies such as implementing feature flags, maintaining a stable core, and thorough testing are essential. Embracing these strategies and recognizing the implications of Hyrum’s Law, which suggests that users will depend on all observable behaviors, can help developers manage API evolution more effectively. Tools like Speakeasy provide support for creating resilient SDKs, emphasizing the importance of versioning and continuous testing to ensure seamless API integration and evolution.