Where is it? Find the tutorial on the Code Capsules Docs.
What is it? A detailed look at how to create a web application that allows users to buy products through Stripe Checkout (a tool for creating a "checkout" process for products) and subscribe to an email list with help from the Mailgun email API service. The last part of the tutorial shows you how to host the web application Code Capsules.
What you need to follow? To complete the tutorial, you'll need a Code Capsules and GitHub account. Programming-wise, the project is best suited for those with some prior Python and Flask experience but you should be able to follow along even without it.