You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

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

    * **CORS**
    * **Cookie Sessions**
    * ...and more.

### Deploy your app (optional)

You can optionally deploy your FastAPI app to [FastAPI Cloud](https://fastapicloud.com), go and join the waiting list if you haven't. 🚀

If you already have a **FastAPI Cloud** account (we invited you from the waiting list 😉), you can deploy your application with one command.

<div class="termy">

```console
$ fastapi deploy

/// tip

When writing the code to document a callback, it might be useful to imagine that you are that *external developer*. And that you are currently implementing the *external API*, not *your API*.

Temporarily adopting this point of view (of the *external developer*) can help you feel like it's more obvious where to put the parameters, the Pydantic model for the body, for the response, etc. for that *external API*.

- MinIO distributed mode requires **fresh directories**. If required, the drives can be shared with other applications. You can do this by using a sub-directory exclusive to MinIO. For example, if you have mounted your volume under `/export`, pass `/export/data` as arguments to MinIO server.
- The IP addresses and drive paths below are for demonstration purposes only, you need to replace these with the actual IP addresses and drive paths/folders.

# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

## Open Internet { #open-internet }

If your app is in the open internet, you wouldn't "trust the network" and let anyone send privileged requests without authentication.

Attackers could simply run a script to send requests to your API, no need for browser interaction, so you are probably already securing any privileged endpoints.

In that case **this attack / risk doesn't apply to you**.

functions even when you are returning a type different than the response model, to be used by the editor and tools like mypy. And still you can have FastAPI do the data validation, documentation, etc. using the `response_model`.

You can also use `response_model=None` to disable creating a response model for that *path operation*, you might need to do it if you are adding type annotations for things that are not valid Pydantic fields, you will see an example of that in one of the sections below....

If you feel lost with all these **"regular expression"** ideas, don't worry. They are a hard topic for many people. You can still do a lot of stuff without needing regular expressions yet.

Now you know that whenever you need them you can use them in **FastAPI**.

## Default values { #default-values }

You can, of course, use default values other than `None`.

### AI-assisted contributions

If you use AI tools when contributing to Gradle, please review our [AI Policy](AI_POLICY.md).

### Additional help

If you run into any trouble, please reach out to us on the issue you are working on.
There is a `#contributing` channel on the community Slack which you can use
to ask any questions.

## Finding issues to work on

### Motivation

This library makes it easy to test that your app Does The Right Thing when it
makes HTTP and HTTPS calls. It lets you specify which responses to return and
then verify that requests were made as expected.

Because it exercises your full HTTP stack, you can be confident that you're
testing everything. You can even copy & paste HTTP responses from your real web
server to create representative test cases. Or test that your code survives in