This a simple API used to interface with Pay Pal's Subscription API. It is built off a Node.js/Express server and handles creating a subscription, checking if a subscription is active and canceling a subscription. Needed is your Client ID and Secret ID generated from your Pay Pal business dashboard. Sandbox keys and URL's are interchangable. Please refer for to Pay Pal API Docs https://developer.paypal.com/docs/api/overview/. Additional logic is needed for user flow from end to end which would consist of a user model on your backend database to persist Pay Pal's Subscriber ID which will be your point of reference for API calls. Each call initializes in exchaging your Client ID and Secret ID for an authorization token. You can skip this and continue to pass your Client ID and Secret ID in the API call and still get the same results (not recomended).