Installation — Flask Documentation (2.2.x) (2023)

Python Version¶

We recommend using the latest version of Python. Flask supports Python3.7 and newer.

Dependencies¶

These distributions will be installed automatically when installing Flask.

Werkzeug implements WSGI, the standard Python interface betweenapplications and servers.
Jinja is a template language that renders the pages your applicationserves.
MarkupSafe comes with Jinja. It escapes untrusted input when renderingtemplates to avoid injection attacks.
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ItsDangerous securely signs data to ensure its integrity. This is usedto protect Flask’s session cookie.
Click is a framework for writing command line applications. It providesthe flask command and allows adding custom management commands.

Optional dependencies¶

These distributions will not be installed automatically. Flask will detect anduse them if you install them.

Blinker provides support for Signals.
python-dotenv enables support for Environment Variables From dotenv when running flaskcommands.
Watchdog provides a faster, more efficient reloader for the developmentserver.

greenlet¶

You may choose to use gevent or eventlet with your application. In thiscase, greenlet>=1.0 is required. When using PyPy, PyPy>=7.3.7 isrequired.

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These are not minimum supported versions, they only indicate the firstversions that added necessary features. You should use the latestversions of each.

Virtual environments¶

Use a virtual environment to manage the dependencies for your project, both indevelopment and in production.

What problem does a virtual environment solve? The more Python projects youhave, the more likely it is that you need to work with different versions ofPython libraries, or even Python itself. Newer versions of libraries for oneproject can break compatibility in another project.

Virtual environments are independent groups of Python libraries, one for eachproject. Packages installed for one project will not affect other projects orthe operating system’s packages.

Python comes bundled with the venv module to create virtualenvironments.

Create an environment¶

Create a project folder and a venv folder within:

$ mkdir myproject$ cd myproject$ python3 -m venv venv

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Activate the environment¶

Before you work on your project, activate the corresponding environment:

$ . venv/bin/activate

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Your shell prompt will change to show the name of the activatedenvironment.

Install Flask¶

Within the activated environment, use the following command to installFlask:

$ pip install Flask

Flask is now installed. Check out the Quickstart or go to theDocumentation Overview.