TypeSpec - a new API description language from @Microsoft acts as an alternative way to author API specifications. typespec.io

Despite OpenAPI's prevalence, TypeSpec aims to cater to diverse developer needs with features that simplify API-first practices.

Microsoft designed TypeSpec to support the Microsoft Graph, providing a design-first, code-like API description language that promotes consistency and ease.

TypeSpec offers: Lightweight language Seamless OpenAPI integration Customizable API guidelines in reusable code

TypeSpec emits OpenAPI specs via a configuration setting, allowing it to act as a layer under OpenAPI while maintaining compatibility.