The Post-OpenAPI Era in API design marks a pivotal shift towards innovative frameworks like Microsoft TypeSpec, TaxiLang, Fern, and Apple Pkl, offering solutions beyond OpenAPI’s constraints. This talk dives into how these frameworks transform API design, providing flexibility, expressiveness, and improved developer experiences. We’ll explore the features and advantages of each framework, demonstrating their potential to enhance API documentation, client generation, and collaborative design processes. Highlighting real-world case studies, we illustrate the positive impact on development speed, usability, and end-user satisfaction. Attendees will gain insights into integrating these frameworks into development workflows, understanding the future landscape of API development, and envisioning the possibilities this new era brings.