||This article provides insufficient context for those unfamiliar with the subject. (April 2012)
Flask is a lightweight web application framework written in Python and based on the Werkzeug WSGI toolkit and Jinja2 template engine. It is BSD licensed.
Flask is called a microframework because it keeps the core simple but extensible. There is no database abstraction layer, form validation, or any other components where third-party libraries already exist to provide common functionality. However, Flask supports extensions, which can add such functionality into an application as if it was implemented in Flask itself. There are extensions for object-relational mappers, form validation, upload handling, various open authentication technologies, and more.
Flask was created by Armin Ronacher. "It came out of an April Fool's joke but proved popular enough to make into a serious application in its own right.".
Flask is inspired by Sinatra.
- Contains development server and debugger
- Integrated support for unit testing
- RESTful request dispatching
- Uses Jinja2 templating
- Support for secure cookies (client side sessions)
- 100% WSGI 1.0 compliant
- Extensive documentation
- Google App Engine Compatibility
- Extensions available to enhance features desired.
Following code shows a simple web application that prints "Hello World!":
from flask import Flask
app = Flask(__name__)
return "Hello World!"
if __name__ == "__main__":
Web applications built on Flask 
See also 
External links