Swagger is an open-source software framework that helps developers design, build, document, and consume [[RESTful]] web services. It provides a set of tools and specifications that enable developers to describe the structure and functionality of their APIs in a machine-readable format. OpenAPI Specification ([[OAS]]), formerly known as Swagger Specification, is a specification for defining RESTful APIs. It is based on the Swagger framework and provides a standard way to describe APIs using JSON or YAML formats. OAS allows developers to define endpoints, request/response formats, authentication methods, parameters, and more. The [[OpenAPI Initiative|Open API]] ([[OAI]]) is a collaborative project that aims to standardize the evolution, promotion, and adoption of the OpenAPI Specification. It was created by several industry leaders including Google, IBM, Microsoft, and others to ensure the longevity and widespread usage of OAS. In summary, Swagger is a software framework for designing RESTful APIs while OpenAPI Specification (formerly Swagger Specification) is a specification for describing those APIs. The OpenAPI Initiative oversees the development and maintenance of the OpenAPI Specification.