API

Where a webhook pushes events out, an API lets you ask questions and give instructions: look up a contact, create a booking, update a record. Most business software exposes a web API, usually over HTTPS with JSON payloads, protected by an API key or OAuth token.

APIs are what make real-time integration possible. A receptionist that can call a calendar API during a conversation can tell the caller the next free slot rather than promising that someone will get back to them.

Using an API directly needs some development work and credential management; integration platforms such as Zapier wrap common APIs so that non-developers can connect them.