The words API and webhook sound like programmer speak, yet the principle behind them is surprisingly simple, and you meet them daily without knowing it. Let us explain clearly what an API and a webhook are, how they work and the difference between them.

What an API is

An API is an interface through which two programs communicate. Imagine a waiter in a restaurant: you (the application) tell your order to the waiter (the API), who takes it to the kitchen (the server) and brings you the finished dish. You do not need to know how the kitchen works, it is enough that you know what to order. That is exactly how a weather app gets data from a meteorological service, how login via Google works on another site and how an e-shop asks for a currency rate.

How an API works

The communication is simple: the application sends a request to a certain address and gets back a response, most often in the clear JSON format. Many APIs require a so-called API key, which is a secret password by which the application proves it has the right to access.

What a webhook is

A webhook works the other way around. Instead of you repeatedly asking the API “is it done yet?”, a webhook notifies you itself when something happens. It is the principle of “do not call us, we will call you”. An example: a customer pays in an e-shop, the payment gateway sends a webhook to your server, and it automatically marks the order as paid. You watch nothing, the message comes by itself at the moment of the event.

API versus webhook: what is the difference

  • With an API you ask when you need something (you pull the data).
  • With a webhook the system notifies you when an event occurs (it pushes the data to you).

The two are often combined: through a webhook you learn that something happened, and through an API you pull the details.

Where you use it in practice

  • Connecting systems, for example an e-shop with accounting and a warehouse.
  • Automations, when one event triggers another action without manual work.
  • Notifications to Telegram or email when something happens.

APIs and webhooks are also the foundation on which modern AI agents and tools via MCP stand.

What to watch out for

  • Keep API keys secret, they are like a password. They do not belong in public code.
  • Verify webhooks by signature, so you know the message really came from whom it should, and not from a fraudster.
  • The communication should always run over encrypted HTTPS.

Do you need to connect systems or automate processes in your company? Get in touch, we will design a tailored integration, also as part of IT support for companies.