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A Python ASGI web microframework with the same API as Flask

Project description

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Quart is a Python ASGI web microframework. It is intended to provide the easiest way to use asyncio functionality in a web context, especially with existing Flask apps. This is possible as the Quart API is a superset of the Flask API.

Quart aims to be a complete web microframework, as it supports HTTP/1.1, HTTP/2 and websockets. Quart is very extendable and has a number of known extensions and works with many of the Flask extensions.


Quart can be installed via pipenv or pip,

$ pipenv install quart
$ pip install quart

and requires Python 3.7.0 or higher (see python version support for reasoning).

A minimal Quart example is,

from quart import Quart, websocket

app = Quart(__name__)

async def hello():
    return 'hello'

async def ws():
    while True:
        await websocket.send('hello')

if the above is in a file called it can be run as,

$ python

To deploy in a production setting see the deployment documentation.


Quart supports the full ASGI 3.0 specification as well as the websocket response and HTTP/2 server push extensions. For those of you familiar with Flask, Quart extends the Flask-API by adding support for,

  • HTTP/1.1 request streaming.
  • Websockets.
  • HTTP/2 server push.

Note that not all ASGI servers support these features, for this reason the recommended server is Hypercorn.


Quart is developed on GitLab. If you come across an issue, or have a feature request please open an issue. If you want to contribute a fix or the feature-implementation please do (typo fixes welcome), by proposing a merge request.


The best way to test Quart is with Tox,

$ pipenv install tox
$ tox

this will check the code style and run the tests.


The Quart documentation is the best place to start, after that try searching stack overflow, if you still can’t find an answer please open an issue.

API Compatibility with Flask

The Flask API can be described as consisting of the Flask public and private APIs and Werkzeug upon which Flask is based. Quart is designed to be fully compatible with the Flask public API (aside from async and await keywords). Thereafter the aim is to be mostly compatible with the Flask private API and to provide no guarantees about the Werkzeug API.

Migrating from Flask

It should be possible to migrate to Quart from Flask by a find and replace of flask to quart and then adding async and await keywords. See the docs for full details.

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