## Conditional OpenAPI from settings and env vars { #conditional-openapi-from-settings-and-env-vars }

You can easily use the same Pydantic settings to configure your generated OpenAPI and the docs UIs.

For example:

{* ../../docs_src/conditional_openapi/tutorial001_py39.py hl[6,11] *}

Here we declare the setting `openapi_url` with the same default of `"/openapi.json"`.

# Sub Applications - Mounts { #sub-applications-mounts }

If you need to have two independent FastAPI applications, with their own independent OpenAPI and their own docs UIs, you can have a main app and "mount" one (or more) sub-application(s).

## Mounting a **FastAPI** application { #mounting-a-fastapi-application }

* Esos esquemas serán parte del esquema de OpenAPI generado y usados por las <abbr title="User Interfaces – Interfaces de usuario">UIs</abbr> de documentación automática.

## Documentación automática { #automatic-docs }

Los JSON Schemas de tus modelos serán parte del esquema OpenAPI generado y se mostrarán en la documentación API interactiva:

You can customize several metadata configurations in your **FastAPI** application.

## Metadata for API { #metadata-for-api }

You can set the following fields that are used in the OpenAPI specification and the automatic API docs UIs:

| Parameter | Type | Description |
|------------|------|-------------|
| `title` | `str` | The title of the API. |

* Those schemas will be part of the generated OpenAPI schema, and used by the automatic documentation <abbr title="User Interfaces">UIs</abbr>.

## Automatic docs { #automatic-docs }

The JSON Schemas of your models will be part of your OpenAPI generated schema, and will be shown in the interactive API docs:

<img src="/img/tutorial/body/image01.png">

* Эти схемы будут частью сгенерированной схемы OpenAPI и будут использоваться автоматической документацией <abbr title="User Interfaces – Пользовательские интерфейсы">UIs</abbr>.

## Автоматическая документация { #automatic-docs }

JSON Schema ваших моделей будет частью сгенерированной схемы OpenAPI и будет отображаться в интерактивной документации API:

* Diese Schemas werden Teil des generierten OpenAPI-Schemas und werden von den <abbr title="User Interfaces – Benutzeroberflächen">UIs</abbr> der automatischen Dokumentation genutzt.

## Automatische Dokumentation { #automatic-docs }

Die JSON-Schemas Ihrer Modelle werden Teil Ihres OpenAPI-generierten Schemas und in der interaktiven API-Dokumentation angezeigt:

* Esses schemas farão parte do esquema OpenAPI gerado, e serão usados pelas <abbr title="User Interfaces – Interfaces de usuário">UIs</abbr> de documentação automática.

## Documentação automática { #automatic-docs }

Os JSON Schemas dos seus modelos farão parte do esquema OpenAPI gerado para sua aplicação, e aparecerão na documentação interativa da API:

* Remove obsolete vote link. PR [#1289](https://github.com/tiangolo/fastapi/pull/1289) by [@donhui](https://github.com/donhui).
* Allow disabling docs UIs by just disabling OpenAPI with `openapi_url=None`. New example in docs: [Advanced: Conditional OpenAPI](https://fastapi.tiangolo.com/advanced/conditional-openapi/). PR [#1421](https://github.com/tiangolo/fastapi/pull/1421).