The terms Swagger and OpenAPI are often used interchangeably in developer conversations, which can be confusing—especially for those new to API development. While they are closely related, they are not exactly the same thing. Understanding how swagger and OpenAPI fit together can help teams document, design, and maintain APIs more effectively.

Originally, Swagger started as a specification for describing REST APIs in a standard, machine-readable format. Over time, it grew in popularity because it made APIs easier to understand, test, and share. In 2016, the Swagger specification was donated to the Linux Foundation and renamed the OpenAPI Specification (OAS). From that point on, OpenAPI became the official standard, while Swagger evolved into a suite of tools built around that standard.

In simple terms, OpenAPI is the specification, and Swagger is the toolset that helps you work with it. When developers talk about swagger and API documentation, they are often referring to tools like Swagger UI, Swagger Editor, and Swagger Codegen, all of which rely on OpenAPI definitions. OpenAPI defines how an API should be described, while Swagger provides practical tools to visualize, validate, and interact with those descriptions.

Another key difference is governance. OpenAPI is vendor-neutral and community-driven, ensuring long-term stability and broad adoption. Swagger tools, while widely used, are maintained by SmartBear and are just one implementation of the OpenAPI standard.

In modern API workflows, Swagger and OpenAPI are often complemented by other tools. For example, Keploy can help generate test cases from real API traffic, which pairs nicely with OpenAPI-based documentation and testing workflows.

Ultimately, there’s no real “either-or” choice. Swagger and OpenAPI work best together—OpenAPI as the blueprint, and Swagger as the toolbox that brings your API documentation and testing to life.