> For the complete documentation index, see [llms.txt](https://docs.appear.sh/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.appear.sh/explanations/openapi-spec-version.md).

# OpenAPI spec version

When Appear detects your API/service, it **automatically generates an OpenAPI v3.1 specification** and provides it as a link. This serves as a foundation for enhanced API documentation, tooling, and automation.

### **What Appear Does**

* **Generates an OpenAPI v3.1 spec for your API/service** automatically.
* **Provides a direct link** to the spec for easy access and integration.
* **Lays the groundwork** for additional features that leverage OpenAPI for greater value.

### **Why This is Useful**

* **Standardised API Definition** – Ensures your API has an available OAS structure for added flexibility within your existing tooling
* **Instant Access to Documentation** – The OpenAPI spec can be used with Swagger UI, Redoc, and other tools.
* **Easier API Consumption** – Enables automatic SDK generation, testing, and integrations.
* **Future Expansion** – Appear will continue to build on this foundation to offer more insights and automation.

The provides spec reflects the automatically generated descriptions and type definitions, that include any curated changes you make.

### Example:

{% code overflow="wrap" %}

```bash
{
  "openapi": "3.1.0",
  "info": {
    "title": "App API",
    "version": "test-api-routes"
  },
  "servers": [
    {
      "url": "http://localhost:3000/",
      "variables": {

      }
    }
  ],
  "tags": [],
  "paths": {
    "/app-api": {
      "summary": "App API data",
      "parameters": [],
      "post": {
        "tags": [],
        "summary": "Submit App Test",
        "description": "This endpoint accepts a JSON object with a single 'test' field, which must be a string of exactly 5 characters. It processes the input and returns a JSON object containing a 'hello' field, also a string of 5 characters. The service ensures strict adherence to the input and output length constraints.",
        "operationId": "/app-api#post",
        "parameters": [],
        "requestBody": {
          "description": "",
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/Test"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "",
            "headers": {
              "Content-Type": {
                "description": "The [MIME type](https://en.wikipedia.org/wiki/MIME_type) of this content",
                "schema": {
                  "type": "string",
                  "maxLength": 16,
                  "minLength": 16
                },
                "example": "application/json"
              }
            },
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Greet"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Greet": {
        "type": "object",
        "required": [
          "hello"
        ],
        "properties": {
          "hello": {
            "type": "string",
            "maxLength": 5,
            "minLength": 5
          }
        }
      },
      "Test": {
        "type": "object",
        "required": [
          "test"
        ],
        "properties": {
          "test": {
            "type": "string",
            "maxLength": 5,
            "minLength": 5
          }
        }
      }
    }
  }
}
```

{% endcode %}

### **More to Come**

The OpenAPI spec generator is one core concept for Appear. We are working on **leveraging this foundation** to provide deeper API insights, improved documentation, and streamlined workflows. 

***

If you have any queries or require support with the above instructions, please [get in touch](/getting-started/get-in-touch.md) with us.


---

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