What are the difference between Swagger and OpenAPI?

Swagger and OpenAPI are related but distinct terms in the context of API documentation. Here’s a breakdown of their relationship and the key differences between them:


  • Swagger was originally an open-source framework introduced in 2011 by Tony Tam and his team. It aimed to simplify the development of RESTful APIs.
  • Over time, Swagger became synonymous with its specification format for documenting RESTful APIs. The Swagger specification was initially known as Swagger Specification but later renamed to OpenAPI Specification (OAS).
  • Swagger UI, another component of the Swagger framework, provides an interactive user interface for exploring and testing APIs based on the Swagger specification.


  • OpenAPI is the evolution of Swagger. It refers specifically to the OpenAPI Specification, which is a standard, language-agnostic specification for documenting APIs.
  • The OpenAPI Specification defines a format for describing RESTful APIs, including their endpoints, request/response structures, parameters, authentication mechanisms, and more.
  • OpenAPI Specification files are written in either JSON or YAML format and serve as a contract between API providers and consumers, facilitating API design, development, and integration.
  • OpenAPI Specification is managed by the OpenAPI Initiative, a project under the Linux Foundation, and it has gained wide industry support.

Key Differences

  1. Terminology: Swagger is the name of the original framework, whereas OpenAPI refers to the standardized specification format.
  2. Versioning: Swagger 2.0 is an earlier version of the specification, while OpenAPI 3.0 is the latest major version. OpenAPI 3.0 introduced significant improvements and expanded the specification’s capabilities.
  3. Industry Standard: OpenAPI has become the industry standard for API documentation and is widely adopted by organizations, tools, and frameworks.
  4. Governance: The OpenAPI Specification is governed by the OpenAPI Initiative, which ensures its development, evolution, and community involvement.
  5. Ecosystem: The OpenAPI ecosystem includes a variety of tools and libraries that support the specification, making it easier to generate documentation, generate code skeletons, and perform API testing and validation.

In summary, Swagger was the original framework, and OpenAPI is the standardized specification format that evolved from Swagger. OpenAPI has become the de facto standard for documenting RESTful APIs, providing a comprehensive and widely supported approach to API documentation.

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