* Seriously impressive performance. It is <a href="https://github.com/encode/starlette#performance" class="external-link" target="_blank">one of the fastest Python frameworks available, on par with **NodeJS** and **Go**</a>.
* **WebSocket** support.
* In-process background tasks.
* Startup and shutdown events.
* Test client built on HTTPX.
* **CORS**, GZip, Static Files, Streaming responses.

    **FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette.

    And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

## Custom Headers

    You could also use `from starlette.responses import JSONResponse`.

    **FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette.

## Returning a custom `Response`

* `routes`: A list of routes, these are each of the registered *path operations*. They are taken from `app.routes`.

!!! info
    The parameter `summary` is available in OpenAPI 3.1.0 and above, supported by FastAPI 0.99.0 and above.

## Overriding the defaults

    And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

                automatically cancel the request and send the client an error.

                If `auto_error` is set to `False`, when the query parameter is not
                available, instead of erroring out, the dependency result will be
                `None`.

                This is useful when you want to have optional authentication.

# Deployment

Deploying a **FastAPI** application is relatively easy.

## What Does Deployment Mean

To **deploy** an application means to perform the necessary steps to make it **available to the users**.

For a **web API**, it normally involves putting it in a **remote machine**, with a **server program** that provides good performance, stability, etc, so that your **users** can **access** the application efficiently and without interruptions or problems.

在新的 Terminal 里，用以下命令确认 CLI 是否正确安装：

<div class="termy">

```console
$ deta --help

Deta command line interface for managing deta micros.
Complete documentation available at https://docs.deta.sh

Usage:
  deta [flags]
  deta [command]

Available Commands:
  auth        Change auth settings for a deta micro

...
```

</div>

!!! tip "提示"

    **FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette. The same with `Request`.

## Override the default exception handlers

**FastAPI** has some default exception handlers.

    You could also use `from starlette.templating import Jinja2Templates`.

    **FastAPI** provides the same `starlette.templating` as `fastapi.templating` just as a convenience for you, the developer. But most of the available responses come directly from Starlette. The same with `Request` and `StaticFiles`.

## Writing templates

Then you can write a template at `templates/item.html` with, for example:

```jinja hl_lines="7"