> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt.

# The api.yml configuration file

> The api.yml file contains general API configuration when using the Fern Definition format.

Fern Definition isn't recommended for new customers and Fern isn't accepting feature requests for this format. It remains supported for existing users.

A `fern/` folder has a special file called `api.yml`, which includes all the API-wide configuration.

```bash {5}
fern/
├─ fern.config.json
├─ generators.yml
└─ definition/
  ├─ api.yml
  ├─ pet.yml
  ├─ store.yml
  └─ user.yml
```

## API name

This name is used to uniquely identify your API in your organization. If you just have one API, then `api` is a sufficient name.

#### api.yml

```yaml
name: api
```

## API description

You can define a top level API description. This description will come through in the OpenAPI Specification and Postman collection.

#### api.yml

```yaml {2-4}
name: api
docs: | 
  ## Header
  This API provides access to...
```

## API version

You can define your header-based API versioning scheme, such as an `X-API-Version`. The supported versions
and default value are specified like so:

#### api.yml

```yaml
version:
  header: X-API-Version
  default: "2.0.0"
  values:
    - "1.0.0"
    - "2.0.0"
    - "latest"
```

> The api.yml file contains general API configuration when using the Fern Definition format.