What is pythonanywhere.com?

PythonAnywhere is an online Integrated Development Environment (IDE) and Web hosting service based on the Python programming language. It provides in-browser access to server-based Python and Bash Command-line interfaces, along with a code editor with Syntax highlighting. Program files can be transferred to and from the service using the user's browser. Web applications hosted by the service can be written using any WSGI-based application framework.

Reference: Wikipedia

How to create Web application

• Register new PythonAnywhere account or log in existing one.
• Go to "Web" tab, click "Add a new web app" button.
• Click "Next »" button. And select Flask Web framework.
• Then choose the Python version you want.
• In next window you should specify path to your flask app.