Swagger and OpenAPI Are Not the Same Thing, but Here Is Why They Overlap

Swagger was originally both a specification and a set of tools for describing REST APIs, but it became so widely adopted that its specification was donated to a foundation and rebranded as OpenAPI. Today, the term 'Swagger' is used interchangeably to refer to the old spec, the tooling, or OpenAPI itself, which causes frequent confusion. In practice, most Swagger files are OpenAPI-compatible, meaning they can be processed and converted to documentation using the same workflows. Developers are advised to generate API documentation from existing machine-readable files rather than writing it from scratch. Teams are also encouraged to standardize on one term — either Swagger or OpenAPI — to reduce confusion for new members.