cdnjs is a free distributed JS library delivery service.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Python is an interpreted and general-purpose programming language.
PythonAnywhere is an online integrated development environment (IDE) and web hosting service (Platform as a service) based on the Python programming language.