The lightning-fast ASGI server.

---

**Documentation**: [https://www.uvicorn.org](https://www.uvicorn.org)

**Requirements**: Python 3.6+ (For Python 3.5 support, install version 0.8.6.)

Uvicorn is a lightning-fast ASGI server implementation, using [uvloop][uvloop] and [httptools][httptools].

Until recently Python has lacked a minimal low-level server/application interface for
asyncio frameworks. The [ASGI specification][asgi] fills this gap, and means we're now able to
start building a common set of tooling usable across all asyncio frameworks.

Uvicorn currently supports HTTP/1.1 and WebSockets. Support for HTTP/2 is planned.

## Quickstart

Install using `pip`:

```shell
$ pip install uvicorn
```

This will install uvicorn with minimal (pure Python) dependencies.

```shell
$ pip install uvicorn[standard]
```

This will install uvicorn with "Cython-based" dependencies (where possible) and other "optional extras".

In this context, "Cython-based" means the following:

- the event loop `uvloop` will be installed and used if possible.
- the http protocol will be handled by `httptools` if possible.

Moreover, "optional extras" means that:

- the websocket protocol will be handled by `websockets` (should you want to use `wsproto` you'd need to install it manually) if possible.
- the `--reloader` flag in development mode will use `watchgod`.
- windows users will have `colorama` installed for the colored logs.
- `python-dotenv` will be installed should you want to use the `--env-file` option.
- `PyYAML` will be installed to allow you to provide a `.yaml` file to `--log-config`, if desired.

Create an application, in `example.py`:

```python
async def app(scope, receive, send):
    assert scope['type'] == 'http'

    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            [b'content-type', b'text/plain'],
        ],
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })
```

Run the server:

```shell
$ uvicorn example:app
```

---

Uvicorn is BSD licensed (https://github.com/encode/uvicorn/blob/master/LICENSE.md) code.
Designed & built in Brighton, England.
— 🦄  —

[uvloop]: https://github.com/MagicStack/uvloop
[httptools]: https://github.com/MagicStack/httptools
[asgi]: https://asgi.readthedocs.io/en/latest/
