There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps { #webhooks-steps }

# 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 }

Keep class names, function names, modules, file names, and CLI commands unchanged.

### List of English terms and their preferred French translations

Below is a list of English terms and their preferred French translations, separated by a colon («:»). Use these translations, do not use your own. If an existing translation does not use these terms, update it to use them.

tags_metadata = [
    {
        "name": "users",
        "description": "Operations with users. The **login** logic is also here.",
    },
    {
        "name": "items",
        "description": "Manage items. So _fancy_ they have their own docs.",
        "externalDocs": {
            "description": "Items external docs",
            "url": "https://fastapi.tiangolo.com/",
        },
    },
]

app = FastAPI(openapi_tags=tags_metadata)

from contextlib import AsyncExitStack

from starlette.types import ASGIApp, Receive, Scope, Send


# Used mainly to close files after the request is done, dependencies are closed
# in their own AsyncExitStack
class AsyncExitStackMiddleware:
    def __init__(
        self, app: ASGIApp, context_name: str = "fastapi_middleware_astack"
    ) -> None:
        self.app = app
        self.context_name = context_name

Some text
///

/// warning
Some text
///

/// danger
Some text
///

////

//// tab | Info

Tabs and `Info`/`Note`/`Warning`/etc. blocks should have the translation of their title added after a vertical bar (`|`).

See sections `### Special blocks` and `### Tab blocks` in the general prompt in `scripts/translate.py`.

////

## Web- and internal links { #web-and-internal-links }

Some other cloud providers ✨ [**sponsor FastAPI**](../help-fastapi.md#sponsor-the-author){.internal-link target=_blank} ✨ too. 🙇

You might also want to consider them to follow their guides and try their services:

* <a href="https://docs.render.com/deploy-fastapi?utm_source=deploydoc&utm_medium=referral&utm_campaign=fastapi" class="external-link" target="_blank">Render</a>

Also, the best approach was to use already existing standards.

So, before even starting to code **FastAPI**, I spent several months studying the specs for OpenAPI, JSON Schema, OAuth2, etc. Understanding their relationship, overlap, and differences.

## Design { #design }

Then I spent some time designing the developer "API" I wanted to have as a user (as a developer using FastAPI).

 *
 * <p>Remote repositories are used for:
 * <ul>
 *   <li>Resolving artifacts and their metadata</li>
 *   <li>Downloading parent POMs and dependency POMs</li>
 *   <li>Retrieving version information and ranges</li>
 *   <li>Accessing plugin artifacts and their dependencies</li>
 * </ul>
 *
 * <p>Repository validation ensures data integrity by:
 * <ul>

It's difficult to convey emotion in text, use emojis to help. 😅