APIs & Authentication
What is Swagger?
A toolset (and historical predecessor of OpenAPI) for designing, documenting, and consuming REST APIs through a machine-readable schema.
Swagger started in 2010 as an internal API description format at Wordnik, became the de facto standard for documenting REST APIs, and was donated to what is now the OpenAPI Initiative in 2016. The "Swagger Specification" was renamed "OpenAPI Specification"; the brand "Swagger" lives on as a family of tools (Swagger UI, Swagger Editor, SwaggerHub) maintained by SmartBear.
Swagger UI is what most developers actually mean when they say "Swagger": a single-page web app that renders an OpenAPI spec into interactive docs, complete with "Try it out" buttons that fire real requests. Drop a swagger-ui.html next to your API, point it at your openapi.json, and you have docs that never go out of date.
In conversation, "swagger" and "openapi" are often used interchangeably, especially for older codebases that still ship swagger.json (older 2.0 spec) rather than openapi.json (3.x). They are not interchangeable formats: 3.x added significant capability (callbacks, links, richer schemas) and most modern tools assume 3.x.
In the wild
- →A startup shipping
/api/swaggeras live docs powered by Swagger UI - →A team migrating a
swagger.json(2.0) toopenapi.json(3.0) to use newer toolchain features - →SwaggerHub used as the design surface where API contracts are reviewed before backend work starts
How Brand.dev uses swagger
Endpoints in the Brand.dev API where this concept comes up directly.
FAQ
Is Swagger the same as OpenAPI?
Same lineage, different scope. OpenAPI is the spec; Swagger is the open-source and commercial toolchain that originated it and still implements much of it.
Should I still call my spec "Swagger"?
In writing, prefer "OpenAPI" for accuracy. Internally, "Swagger" is fine if your team knows what you mean.
What is the difference between Swagger 2.0 and OpenAPI 3.0?
3.0 split bodies and parameters, added components/schemas reuse, support for multiple servers, callbacks for webhooks, and tighter JSON Schema alignment. Migration is mostly mechanical and well-tooled.
Related terms
A specification format for describing REST APIs in a machine-readable schema, used to generate documentation, client SDKs, and server stubs.
An API that follows REST conventions, using HTTP methods on resource URLs to model create/read/update/delete operations.
An Application Programming Interface, a contract that lets one program request actions or data from another in a stable, documented way.
JavaScript Object Notation, a lightweight text format for representing structured data, supported natively by every modern language.