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Flask is a lightweight WSGI web application framework for Python. This guide will help you install Flask and get your development environment ready.

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Python Version Requirements

Flask requires Python 3.10 or newer. You can check your Python version with: 
python --version
# or
python3 --version
Flask 3.2.0 requires Python 3.10+. If you need to support older Python versions, consider using an earlier Flask release.

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Virtual Environments

It’s strongly recommended to use a virtual environment to manage your project dependencies and avoid conflicts with system-wide packages.
1

Create a project directory

mkdir myproject
cd myproject
2

Create a virtual environment

python3 -m venv .venv
3

Activate the virtual environment

. .venv/bin/activate
Your shell prompt will change to show the name of the activated environment.

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Install Flask

Once your virtual environment is activated, install Flask using pip: 
pip install Flask
This will install Flask along with its core dependencies:
  • Werkzeug (≥3.1.0) - WSGI utilities library
  • Jinja2 (≥3.1.2) - Template engine
  • Click (≥8.1.3) - Command-line interface framework
  • ItsDangerous (≥2.2.0) - Data signing library
  • Blinker (≥1.9.0) - Signal support
  • MarkupSafe (≥2.1.1) - String escaping

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Optional Dependencies

Flask provides optional features that require additional dependencies:

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Async Support

For asynchronous view functions and routes: 
pip install Flask[async]
This installs asgiref for async support.

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Environment Variables from .env Files

To automatically load environment variables from .env files: 
pip install Flask[dotenv]
This installs python-dotenv.

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Install All Optional Dependencies

pip install Flask[async,dotenv]

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Verify Installation

Verify that Flask is installed correctly: 
python -c "import flask; print(flask.__version__)"
You can also use the Flask CLI: 
flask --version
This will display:
  • Python version
  • Flask version
  • Werkzeug version

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Development Installation

If you want to contribute to Flask or install from source:
1

Clone the repository

git clone https://github.com/pallets/flask
cd flask
2

Create and activate a virtual environment

python3 -m venv .venv
. .venv/bin/activate
3

Install in editable mode

pip install -e .
This installs Flask in editable mode, so changes to the source code are immediately available.

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Next Steps

Quickstart

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