Open-source interactive API documentation generated from an OpenAPI spec
Swagger UI is the zero-cost way to give every API a 'try it' page: point it at your OpenAPI file and it renders the endpoints, schemas and a request runner in the browser. It is open source under Apache 2.0 and ships inside most web frameworks' OpenAPI plugins. What it does not do is design, host or govern APIs; that is SmartBear's paid SwaggerHub, which publishes no list prices.
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Swagger UI is a JavaScript application that reads an OpenAPI (formerly Swagger) specification and renders interactive documentation: every path, parameter, schema and example, with a button to send a real request from the page. It runs entirely in the browser, has no server-side component and no dependencies beyond the spec file. The code is on GitHub under the Apache 2.0 licence with about 29,000 stars.
Most teams never install it by hand. FastAPI, Spring Boot (springdoc), NestJS, Django REST Framework and ASP.NET all bundle it, so /docs or /swagger-ui appears the moment you annotate your endpoints. SmartBear, which maintains it, sells SwaggerHub for teams that want hosted design, versioning and governance; SwaggerHub pricing is by quote and trial, not a public rate card.
Quick facts: Apache 2.0 · Browser-only, no backend · Supports Swagger 2.0 and OpenAPI 3.x · Bundled with FastAPI, Spring Boot, NestJS and others · Maintained by SmartBear.
Paths, parameters, request and response schemas and examples come from the OpenAPI file; the docs cannot drift from the contract.
Send real requests from the page with auth headers, and see the curl command, status and body.
API key, HTTP bearer, OAuth 2 and OpenID Connect flows are rendered as login forms in the UI.
Both spec versions are supported, including 3.1 features such as webhooks.
Plugins, custom layouts, a theme CSS file and the full source if you need to change behaviour.
Comes with the OpenAPI plugins of FastAPI, Spring, NestJS, Django REST Framework and ASP.NET Core.
Swagger UI itself has no price. SmartBear's hosted products built around it (Swagger for Teams, Swagger Enterprise, SwaggerHub) are sold through trials and sales, with no public rate card on the pricing page we checked.
| Plan | Price | What you get |
|---|---|---|
| Swagger UI (open source) | $0 | Apache 2.0; self-host or use the framework bundle; no limits |
| Swagger for Teams | No price listed | Interactive editor, hosted documentation, collaboration on files, design auto-mocking; 'Learn more' leads to a trial |
| Swagger Enterprise | Contact sales | API standardisation, teams and projects, reusable domains, on-premise installation |
Source: swagger.io/tools/swagger-ui, checked 22 Oct 2026. Licence confirmed on github.com/swagger-api/swagger-ui (Apache-2.0). SmartBear's pricing page lists plan names without amounts; third-party sites quote per-user figures that we could not verify.
In the order a small team would do them.
Annotate handlers in your framework so the OpenAPI file is built on every run and cannot go stale.
Keep /docs behind auth or on an internal host; publish a sanitised spec for partners separately.
Define an API-key scheme pointing at your sandbox so 'try it out' works without production credentials.
Examples in the spec render in the UI and in generated SDKs; they are the part partners actually read.
Run an OpenAPI linter (Spectral, Redocly CLI) on every pull request so a broken spec never reaches the docs page.
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