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flask hello world

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In this tutorial you’ll learn how to build a web app with Python.

We’ll use a micro-framework called Flask. It has a small core but is extensible with many plugins such as SQLAlchemy, Babel, CouchDB, MongoDB etc.

Some Flask example apps are:

Related course
Python Flask: Make Web Apps with Python

  • easy to use.
  • built in development server and debugger
  • integrated unit testing support
  • RESTful request dispatching
  • uses Jinja2 templating
  • support for secure cookies (client side sessions)
  • 100% WSGI 1.0 compliant
  • Unicode based
  • extensively documented

Download Flask Examples

Installing Flask

Install Flask using the command below:

pip install Flask

Flask hello world app

Create a file called

from flask import Flask
app = Flask(__name__)

def hello():
return "Hello World!"

if __name__ == "__main__":

Finally run the web app using this command:

$ python
* Running on http://localhost:5000/

Open http://localhost:5000/ in your webbrowser, and “Hello World!” should appear.

Download Flask Examples


Leave a Reply:

Robert Walsh Fri, 17 Jul 2015

what if flask will not install on python?

Frank Fri, 17 Jul 2015

You can install Flask with pip, easy_install or another tool depending on your operating system.

Michael Fri, 21 Aug 2015

can i ask any question frank?

Frank Fri, 21 Aug 2015

sure, ask anything you want.