> ## Documentation Index
> Fetch the complete documentation index at: https://payload-plugin-openapi.seshuk.im/llms.txt
> Use this file to discover all available pages before exploring further.

# OpenAPI version

> The document is always built as OpenAPI 3.2; openapiVersion downconverts the result to 3.1 or 3.0.

The builder always produces an OpenAPI 3.2 document. The `openapiVersion` option controls what gets served — `'3.1'` and `'3.0'` each run a downconversion pass on the finished document:

| Version | Behavior                                                                      |
| ------- | ----------------------------------------------------------------------------- |
| `'3.2'` | Served as built (default)                                                     |
| `'3.1'` | A downconversion pass strips 3.2-only fields                                  |
| `'3.0'` | A downconversion pass to 3.0 (e.g. nullable handling, `examples` → `example`) |

```ts payload.config.ts theme={null}
openapi({
  metadata: { title: 'My API', version: '1.0.0' },
  openapiVersion: '3.0',
})
```

## Nested tags

<Note>
  Scalar and Swagger UI don't render OpenAPI 3.2 nested tags yet. The `nestedTags` option is **off by default**, so
  `doc.tags` is a flat list of per-entity tags with descriptions. Turn it on only if your consumer understands the 3.2
  `kind`/`parent` tag tree.
</Note>

When `nestedTags: true`, the plugin emits the 3.2 tag hierarchy: navigation groups via `kind`/`parent`, plus per-entity auth and version sub-tags.

## Downconverting yourself

The downconverters are also exported as `toOpenApi30` and `toOpenApi31`, so you can build a 3.2 document programmatically and convert it in your own code. See [Exports](/reference/exports).