Swagger

The name that launched a thousand API docs pages. Swagger started as both a specification and a set of tools for designing, building, and documenting REST APIs. In 2016, the specification part was donated to the Linux Foundation and rebranded as OpenAPI, but the Swagger name lived on as the toolkit brand under SmartBear. So now “Swagger” refers to the tools — Swagger UI, Swagger Editor, Swagger Codegen — while “OpenAPI” refers to the spec itself. Yes, people still use the names interchangeably. No, it doesn’t really matter in casual conversation.

Swagger UI remains one of the most recognizable tools in the API ecosystem: that interactive documentation page where you can expand endpoints, fill in parameters, and hit “Try it out” to fire real requests. It turned API documentation from a static PDF nobody reads into a living, clickable playground. Swagger Editor lets you write OpenAPI specs with real-time validation, and Swagger Codegen generates client libraries and server stubs in dozens of languages. Together, they form a workflow that makes API-first development feel almost enjoyable.

Why it matters: Swagger’s tooling democratized API documentation and made interactive, always-up-to-date docs the standard rather than the exception. Even though the spec is now called OpenAPI, Swagger’s tools remain the most popular way to bring those specs to life.