API providers need to understand how their consumers are using their APIs. Usage metrics are essential because they tell you about API adoption, how your API is growing over time, and which endpoints are seeing more (or less) use. When you look at API usage metrics, you should be measuring the active users on your API in the sense that most closely aligns with your service. This informs where your organization allocates compute resources, which API endpoints you decide to develop, and which API endpoints you document.

What is an active user? At first glance, it may seem like simply tracking the number of users using an endpoint. But API users can’t be tracked in the same way as website users. Instead, you need to look at how your users access your API in the context of your product.