Webhook or API: what is the difference?

An API is how you ask an app for data. A webhook is how the app tells you without being asked. Same two apps, opposite direction of the first move.

The short version

• API call: your tool sends a request and the other app answers. You decide when.
• Webhook: the other app sends your tool a message when an event happens. It decides when.

GitHub's documentation draws the same line. Webhooks deliver data as it happens, whereas polling an API means calling it every so often to see whether anything is new.¹

What polling looks like

Polling is the plain, repeated version of asking. Your automation tool checks an app on a schedule and asks, "Anything new since last time?" Make describes the contrast directly. Scheduled triggers periodically ask a service for new data, while webhooks run the scenario straight after the URL receives a request.²

Zapier has a polling option too. Its Retrieve Poll trigger makes a GET request of an outside URL to check for new entries.³ A GET request is just a "please give me this" message.

When a webhook fits

• You want to react quickly. GitHub says webhooks give near real-time updates because they're triggered when an event happens.¹
• You're watching many things at once. GitHub points out that calling an API for each resource can use up your rate limit quota fast, while webhooks only send information when something happens.¹
• The app offers one. Many apps provide webhooks that run a Make scenario whenever a certain change happens in the app.²

When an API call fits

GitHub says an API call is fine in two cases. One is when you only need information once or now and then. The other is when you only watch a small set of resources and don't plan to grow.¹

Think of looking up a customer's order status when a person asks for it. There's no event to wait for. You just ask.

Make also notes that when an app doesn't provide webhooks, you can poll the service for new data on a schedule.²

A quick way to tell which one a tool is using

Look at the wording in the tool's settings.

• Words like "instant" or "catch hook" point to a webhook. Make marks its webhook-based triggers INSTANT, and Zapier's webhook trigger is called Catch Hook.²³
• Words like "poll" or "retrieve poll" point to a tool that asks on a schedule. Check the tool's own help page for the timing.
• A "webhook URL" appears when you're on the receiving side. You copy that address to the sending app. See the webhook URL page.

One catch with webhooks

Because the sender is in charge of timing, you can't slow it down. Zapier warns that webhooks may delay passing data to later steps when many requests arrive at once.³

An API call is different. You control the pace, so a burst only happens if you make one.

Neither option is better on its own. They answer different questions. If you're unsure of the basics, start with what a webhook is. To see what actually arrives, open the page on message contents.