Swagger is a toolchain for the implementation and documentation of REST APIs while consistently following the idea that users can directly try out APIs.

Swagger is basically three things in one: a specification format, a collection of open source tools, and a commercial offering. Its tools not only generate API references in a semi-automatically manner, but also provide suitable client SDKs for numerous programming languages to consume this specification. It consists of a core library (»Swagger Core«), an interface for visualization and test calls (»Swagger UI«), a code generator (»Swagger Codegen«), and an editor (»Swagger Editor«).

In 2016, the specification part of Swagger has been moved/transferred to OpenAPI in order to remain vendor-neutral and to better handle the different interests and suggestions for improvement while the open source tools, and a commercial offering continue to be offered under the name »Swagger«.