---
id: flask
version: "3.1.3"
license: BSD-3-Clause
license_treatment: permissive
maintenance: active
---

# Flask — A simple framework for building complex web applications.

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install flask
uv add flask
poetry add flask

## Description

<div align="center"><img src="https://raw.githubusercontent.com/pallets/flask/refs/heads/stable/docs/_static/flask-name.svg" alt="" height="150"></div>

# Flask

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.

[WSGI]: https://wsgi.readthedocs.io/
[Werkzeug]: https://werkzeug.palletsprojects.com/
[Jinja]: https://jinja.palletsprojects.com/

## A Simple Example

```python
# 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)
```

## Donate

The Pallets organization develops and supports Flask and the libraries
it uses. In order to...

## AI interpretation — verify before relying

Flask is a lightweight WSGI web framework for building web applications from simple to complex, with minimal enforcement of structure or dependencies.

Verdict: Flask is a production-stable, actively maintained web framework with no known vulnerabilities, low install friction, and permissive licensing. Its minimal dependencies and broad adoption make it a reliable choice for web application development.

[View on SkillFed](https://skillfed.io/packages/flask) · [View on PyPI](https://pypi.org/project/flask/)