/// info

For more information, check [the official Python docs](https://docs.python.org/3/library/__main__.html).

///

## Run your code with your debugger { #run-your-code-with-your-debugger }

Because you are running the Uvicorn server directly from your code, you can call your Python program (your FastAPI application) directly from the debugger.

---

For example, in Visual Studio Code, you can:

* Go to the "Debug" panel.

## Pin your `fastapi` version { #pin-your-fastapi-version }

The first thing you should do is to "pin" the version of **FastAPI** you are using to the specific latest version that you know works correctly for your application.

For example, let's say you are using version `0.112.0` in your app.

Follow your cloud provider's guides to deploy FastAPI apps with them. 🤓

## Deploy your own server { #deploy-your-own-server }

You must agree to the terms of [Developer Certificate of Origin](https://developercertificate.org/) by signing off your commits. We automatically verify that all commit messages contain a `Signed-off-by:` line with your email address. We can only accept PRs that have all commits signed off.

If you didn't sign off your commits before creating the pull request, you can fix that after the fact.

To sign off a single commit:

**"Dependency Injection"** means, in programming, that there is a way for your code (in this case, your *path operation functions*) to declare things that it requires to work and use: "dependencies".

And then, that system (in this case **FastAPI**) will take care of doing whatever is needed to provide your code with those needed dependencies ("inject" the dependencies).

This is very useful when you need to:

# Request Body { #request-body }

When you need to send data from a client (let's say, a browser) to your API, you send it as a **request body**.

A **request** body is data sent by the client to your API. A **response** body is the data your API sends to the client.

### Install requirements

Create a virtual environment and install the required packages with [`uv`](https://github.com/astral-sh/uv):

<div class="termy">

```console
$ uv sync --extra all

---> 100%
```

</div>

It will install all the dependencies and your local FastAPI in your local environment.

### Using your local FastAPI

### Server Memory { #server-memory }

For example, if your code loads a Machine Learning model with **1 GB in size**, when you run one process with your API, it will consume at least 1 GB of RAM. And if you start **4 processes** (4 workers), each will consume 1 GB of RAM. So in total, your API will consume **4 GB of RAM**.

You have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

# OpenAPI Webhooks { #openapi-webhooks }

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**.