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# Base path

> Configure base paths in OpenAPI with `x-fern-base-path`. Set up endpoint prefixes like /v1 for your API definitions with Fern.

Use the `x-fern-base-path` extension to configure the base path prepended to every endpoint.

The example below configures the `/v1` base path so the full endpoint path is
`https://api.example.com/v1/users`.

**`Set the base path in openapi.yml`**

```yaml title="Set the base path in openapi.yml" {1}
x-fern-base-path: /v1
servers:
  - url: https://api.example.com
paths:
  /users: ...
```

A plain base path applies to the whole API, so in a project with multiple OpenAPI specs only one document's value survives the merge. Enable [`respect-per-spec-base-path`](/learn/api-definitions/openapi/generators-yml-reference#settingsrespect-per-spec-base-path) to give each spec its own base path.

> Configure base paths in OpenAPI with `x-fern-base-path`. Set up endpoint prefixes like /v1 for your API definitions with Fern.