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_:
.. code-block:: text
pip install -U Flask
.. code-block:: python
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
return "Hello, World!"
.. code-block:: text
$ env FLASK_APP=hello.py flask run
* Serving Flask app "hello"
* 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_.
.. _contributing guidelines: https://github.com/pallets/flask/blob/master/CONTRIBUTING.rst
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_.
.. _please donate today: https://psfmember.org/civicrm/contribute/transact?reset=1&id=20
- Website: https://palletsprojects.com/p/flask/
- Documentation: https://flask.palletsprojects.com/
- Releases: https://pypi.org/project/Flask/
- Code: https://github.com/pallets/flask
- Issue tracker: https://github.com/pallets/flask/issues
- Test status: https://dev.azure.com/pallets/flask/_build
- Official chat: https://discord.gg/t6rrQZH
.. _WSGI: https://wsgi.readthedocs.io .. _Werkzeug: https://www.palletsprojects.com/p/werkzeug/ .. _Jinja: https://www.palletsprojects.com/p/jinja/ .. _pip: https://pip.pypa.io/en/stable/quickstart/