> For the complete documentation index, see [llms.txt](https://syndrom.gitbook.io/syndrom/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://syndrom.gitbook.io/syndrom/basics/openapi.md).

# OpenAPI

Our SaaS boilerplate comes with built-in API documentation powered by OpenAPI (formerly known as Swagger). This feature provides a comprehensive and interactive documentation of your backend API, making it easier for developers to understand and interact with the available endpoints.

#### Accessing the API Documentation

Once your backend server is running, you can access the OpenAPI documentation by following these steps:

1. Ensure your backend server is running (typically on port 4001).
2. Open a web browser and navigate to:

   ```
   Copyhttp://localhost:4001/api
   ```
3. You will be presented with the OpenAPI UI, showing all available endpoints, request/response schemas, and other API details.

#### Features of the OpenAPI Documentation

1. **Interactive Interface**: The OpenAPI UI allows you to not only read about the API endpoints but also try them out directly from the browser.
2. **Detailed Endpoint Information**: For each endpoint, you can see:
   * The HTTP method (GET, POST, PUT, DELETE, etc.)
   * The route
   * Required parameters
   * Request body schema (for POST and PUT requests)
   * Response schemas
   * Authentication requirements
3. **Model Schemas**: View detailed schemas for all data models used in your API.
4. **Try It Out**: You can make actual API calls directly from the documentation interface to test endpoints.

#### Benefits of OpenAPI Documentation

* **Easy Onboarding**: New developers can quickly understand the API structure and capabilities.
* **Testing**: Easily test API endpoints without needing to set up a separate API client.
* **Client Generation**: The OpenAPI specification can be used to generate client libraries in various programming languages.
* **Always Up-to-Date**: As the documentation is generated from your code, it always reflects the current state of your API.

#### Extending the Documentation

As you add new endpoints or modify existing ones, the OpenAPI documentation will automatically update to reflect these changes. However, to make the most of this feature:

1. Use appropriate NestJS decorators and TypeScript types in your controllers and DTOs.
2. Add meaningful descriptions to your endpoints and DTO properties using OpenAPI decorators.

Example of enhanced documentation in a controller:

```typescript
typescriptCopyimport { ApiOperation, ApiResponse, ApiTags } from '@nestjs/swagger';

@ApiTags('products')
@Controller('products')
export class ProductsController {
  @Get()
  @ApiOperation({ summary: 'Get all products' })
  @ApiResponse({ status: 200, description: 'Return all products.' })
  async findAll() {
    // ...
  }
}
```

By leveraging the OpenAPI documentation, you can ensure that your API is well-documented and easily accessible to all developers working on your SaaS project.

Remember to keep your API documentation secure if it contains sensitive information about your backend structure.

<figure><img src="https://1133247628-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FChP1QKunnIyhe3OuxmcV%2Fuploads%2Fp3sa769mkt8a2lrTK8Hj%2Fimage.png?alt=media&amp;token=e4586e63-5395-4930-a956-d41a1f0a7afe" alt=""><figcaption></figcaption></figure>