# API version

> Configure API version schemes and headers using `x-fern-version` extension

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

```yaml title="openapi.yaml"
x-fern-version:
  header: X-API-Version
  default: "2.0.0"
  values:
    - "1.0.0"
    - "2.0.0"
    - "latest"
paths: ...
```