Is a webhook an API?

The biggest difference is in how they communicate. A traditional API works on the "pull" principle: your system actively requests information from another system. Imagine your Web shop asking your inventory system every hour, "How many products do we have left?" Even if nothing has changed, your system keeps asking this question. On the contrary, a webhook works on the "push" principle: the other system automatically sends information to your system when something changes. In this case, your inventory system would only send a message when a product's inventory drops below a certain level. You don't have to keep asking, you automatically get a message when something important happens.

This difference makes webhooks more efficient in many situations. They use less bandwidth because they only send data when there is really something to report. For your server, this means less work and lower costs. However, you do have to make sure your system is reachable for these messages, which requires certain security measures.

In practice, both techniques are often used together. For example, a web shop might use webhooks to hear instantly when a new order arrives, while at the same time it uses an API to retrieve product information when a customer visits the website. So a webhook is not an API per se, but a specific way of communicating within the broader API landscape. It is a powerful method that is especially useful for real-time updates and events. By understanding the difference, you can make smarter choices for your own systems.