The Web Server Gateway Interface (WSGI) is a Python specification that allows for a Python executable to be used to respond to web requests. WSGI is built into Python web frameworks such as Flask and Django.

To enable the use of the Flask web framework to serve web pages, some configuration of IIS is required, including the installation of an IIS Common Gateway Interface (CGI) module called FastCGI, and the installation of a Python module called WFastCGI. With these two additions, the IIS web server will connect to the code behind the API application.