Webhooks and APIs without fear

At some point a workflow needs something the visual tool does not have a ready-made block for. That is when you meet APIs and webhooks. Both are simpler than their reputation.

The analogy

• An API is a counter you walk up to. You ask ("give me the open invoices for customer 42"), you wait, you get an answer.
• A webhook is a delivery driver. You give a service your address, and it drops a package at your door whenever something happens ("invoice 1071 was paid").

APIs are for asking. Webhooks are for being told.

Calling an API from a workflow

Most workflow tools have an "HTTP request" step. Four fields matter:

The response comes back as JSON too. Your tool will let you pick fields out of it for the next step.

Receiving a webhook

Create a "webhook trigger" in your tool. It gives you a URL. Paste that URL into the other service's "notify me at" setting. From then on, every event starts your workflow with the event's data as input.

Two rules:

• Verify the sender. Most services sign their webhooks. Your tool usually has a toggle to check the signature; turn it on.
• Expect duplicates. Services retry when they do not hear back. Make the workflow safe to run twice with the same event (check "have I already handled event 1071?" before acting).

Before you call anything

• [ ] I know whether this call reads or changes data.
• [ ] The token is stored as a secret.
• [ ] I have tried the call once by hand (most docs have a "try it" button).
• [ ] I know the rate limit and what happens if I exceed it.

Try it

Pick a service you already pay for. Find its API documentation page. Make one GET call from your workflow tool and print the result. That first successful call removes most of the fear.