OpenAPI / Swagger Viewer

Paste an OpenAPI 3.x or Swagger 2.x spec (YAML or JSON) and explore endpoints visually.

Sample APIv1.0.0

A simple example OpenAPI specification

6 endpoints

Users

GET
/users

List all users

DELETE
/users

Delete a user

GET
/users/{id}

Get a user by ID

DELETE
/users/{id}

Delete a user

GET
/users/{id}

Get a user by ID

DELETE
/users/{id}

Delete a user

Frequently Asked Questions

What formats does the OpenAPI Viewer support?

It supports OpenAPI 3.x YAML and JSON, and Swagger 2.x JSON.

Does it validate the specification?

It parses and renders the specification but does not perform full JSON Schema validation. For full validation, use swagger-cli or spectral.

Can I import a spec from a URL?

URL import is not supported in this version. Paste your spec directly into the editor.

Is my spec sent to any server?

No. All parsing and rendering happens entirely in your browser.

What is the OpenAPI Specification?

The OpenAPI Specification (OAS) is a standard, language-agnostic format for describing HTTP APIs. It defines your API's endpoints, operations (GET, POST, etc.), request/response schemas, authentication, and more — all in a single YAML or JSON file. Clients, servers, and tools can read this file to generate documentation, SDK code, test mocks, and type-safe clients automatically.

Swagger was the original name of the specification; it was donated to the Linux Foundation in 2016 and renamed OpenAPI. Swagger 2.0 and OpenAPI 3.x are the two major versions still in active use. OpenAPI 3.1 (released 2021) aligns fully with JSON Schema Draft 2020-12.

OpenAPI 3.x File Structure

openapi: 3.1.0
info:
  title: My API
  version: 1.0.0
servers:
  - url: https://api.example.com/v1
paths:
  /users/{id}:
    get:
      summary: Get user by ID
      parameters:
        - name: id
          in: path
          required: true
          schema: { type: integer }
      responses:
        '200':
          description: A user object
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/User'
components:
  schemas:
    User:
      type: object
      properties:
        id: { type: integer }
        name: { type: string }

OpenAPI Ecosystem Tools

  • Swagger UI / Redoc — generate interactive HTML documentation from a spec file.
  • Stoplight Studio — GUI editor for writing OpenAPI specs visually.
  • openapi-generator — generate client SDKs (TypeScript, Python, Java, Go, etc.) from a spec.
  • Spectral — linter for OpenAPI specs; enforce custom style rules across your API.
  • Prism — mock server that serves example responses from a spec file during development.
  • tRPC / GraphQL — alternatives to REST+OpenAPI that have type-safe APIs built-in.