Quart is now a Pallets project

written by P G Jones on 2022-07-06 in Meta

Quart, an ASGI re-implementation of the Flask API has joined the Pallets organization. This means that future development will be under the Pallets governance by the Pallets maintainers.

Our long term aim is to merge Quart and Flask to bring ASGI support directly to Flask. This aim has significant technical obstacles, as outlined in this post or this talk. However, this change clears governance obstacles and brings the Quart and Flask maintainers closer together.

Introduction to Quart

Quart was developed from a desire to use asyncio and the async/await keywords in Flask. Which at the time of Quart's inception was not possible in Flask nor was it possible to add support. Instead Quart was developed as a reimplementation of Flask's API using async/await (learn more from this talk). Later Quart adopted the ASGI standard and is now a compliant ASGI framework.

The Quart API is a superset's of Flask in that it matches Flask's whilst including ASGI specific features such as websockets, for example:

from quart import Quart, render_template, websocket

app = Quart(__name__)

async def hello():
    return await render_template("index.html")

async def json():
    return {"hello": "world"}

async def ws():
    while True:
        await websocket.send("hello")
        await websocket.send_json({"hello": "world"})

You can read more about Quart at quart.palletsprojects.com including a guide to migrating from Flask to Quart.

When to use Quart

Quart is an ASGI framework utilising async IO throughout, whereas Flask is a WSGI framework utilising sync IO. It is therefore best to use Quart if you intend to use async IO (i.e. async/await libraries) and Flask if not. Don't worry if you choose the 'wrong' framework though, as Quart supports sync IO and Flask supports async IO, although less efficiently.

What's next

The large ecosystem of Flask extensions is a real strength but unfortunately these extensions only work with Flask, and vice versa for Quart extensions. Therefore we plan to enable extensions to support both Flask and Quart in the future.

We expect to keep developing features for both Flask and Quart, in fact a number of features now present in Flask were developed in Quart or from knowledge gained from Quart. This includes typing, async/await support (in Flask), faster routing, and more.

With the closer relationship now possible both Flask and Quart should benefit from new features, shared bug fixes, and more. Please join our discord if you'd like to get involved.