Both Django and Flask are free and open source and have an enthusiastic following worldwide.
Django was developed in 2005 and is a cross-platform full-stack framework with BSD license. Originally conceived as Django CMS, it’s now suitable for a variety of different web applications. Django follows the DRY principle (“Don’t repeat yourself”) and offers an all-round solution for building and maintaining websites or other web developments. Being a reliable and well-documented framework, Django is used by Instagram, Spotify, and YouTube, among others.
In contrast to Django, the micro-framework Flask by Austrian developer Armin Ronacher released in 2010 takes a minimalist approach. It doesn’t include much more than a library “tool” for the creation of WSGI applications and the template engine Jinja. Flask doesn’t provide any other components. However, developers can easily integrate existing libraries and add numerous features, while retaining a slim core in Flask. The framework has a free BSD license and is used by Netflix, Reddit and Airbnb, among others.