Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. It began as a simple wrapper around Werkzeug and Jinja and has become one of the most popular Python web application frameworks.

Flask offers suggestions, but doesn't enforce any dependencies or project layout. It is up to the developer to choose the tools and libraries they want to use. There are many extensions provided by the community that make adding new functionality easy.

Install and update using pip:

$ pip install -U Flask

# save this as app.py
from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, World!"

$ flask run
  * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

For guidance on setting up a development environment and how to make a contribution to Flask, see the contributing guidelines.

The Pallets organization develops and supports Flask and the libraries it uses. In order to grow the community of contributors and users, and allow the maintainers to devote more time to the projects, please donate today.

• Documentation: https://flask.palletsprojects.com/
• Changes: https://flask.palletsprojects.com/changes/
• PyPI Releases: https://pypi.org/project/Flask/
• Source Code: https://github.com/pallets/flask/
• Issue Tracker: https://github.com/pallets/flask/issues/
• Website: https://palletsprojects.com/p/flask/
• Twitter: https://twitter.com/PalletsTeam
• Chat: https://discord.gg/pallets