Flask App with Google Login

A very good guide from Real Python.

Real Python's Create a Flask Application With Google Login by Alexander VanTol

The only change I made to test it locally was removing pyOpenSSL. So, for testing I ran it on http://127.0.0.1:5000. That's what I set in Google Cloud Console.

Also, for testing locally / development purposes only, set the environment variable OAUTHLIB_INSECURE_TRANSPORT=1 so oauthlib can run in non-HTTPS connection.

Source: ZeroTwo's answer on Stack Overflow.

I found that setting up SSL for localhost is a lot more complicated. It's easier to set SSL of an online website.