Term · Integrations & automation

Webhook

A webhook is a signal from one system to another: something has changed. The other system can then carry on straight away.

Updated 7 October 20263 min read

In short

A webhook is an automatic message that a software package sends to a fixed web address as soon as something happens, such as a paid invoice. With an ordinary API you keep asking yourself whether there is anything new. With a webhook the package reports it itself.

What is a webhook?

A webhook is an automatic message that a software package sends to a fixed web address as soon as something happens. For example: an invoice has been paid, or there is a new customer.

The difference from an API lies in who starts. Via an API, your software keeps asking: is there anything new? With a webhook that is not necessary. The package reports it itself.

How does a webhook work?

You give the package a web address and choose for which events it should send a message. When that happens, the package sends a short message to that address. Software runs there that receives the message and takes the next step.

Often the message only states what has changed, for example a number. The recipient then fetches the data via the API. The payment service Mollie works this way for payments. Exact Online and Moneybird also offer webhooks for developers.

Example in an SME

Made-up example

A customer pays for an order in a webshop. The payment service sends a webhook. The integration sees that the order has been paid, gets it ready for the warehouse and sends the customer a confirmation. Nobody has to go through the payments for this.

What should you look out for?

The address must be reachable. The software that receives the message must be online. That requires hosting.
Check the sender. Anyone can send a message to a web address. So have the recipient check whether the message comes from the right package. Or fetch the data yourself via the API, as Mollie recommends.
Messages can arrive twice or go missing. Some packages try again if a message does not arrive. So the recipient must recognise a duplicate message. And a check at fixed times catches what was missed.

Webhooks are a building block of workflow automation and of many API integrations. Want to know how I build integrations? Read more about integrations and automation.

Frequently asked questions

What is the difference between a webhook and an API?

With an API, your software asks for data itself. With a webhook, the other package sends a message as soon as something changes. They often work together: the webhook reports the change, the API supplies the data.

Does every package have webhooks?

No. Many packages with an API have them, but not all. Without a webhook, an integration can ask at fixed times what is new. That works too, just with some delay.

Can you use webhooks without programming?

Yes, with an integration platform. In n8n and Zapier you can choose an incoming webhook as the starting point of an automation. With Zapier this is only possible with a paid plan.

Sources: Mollie: webhooks, Exact Online: WebhookSubscriptions, Moneybird: webhooks, Webhooks by Zapier, Zapier: plans and n8n: Webhook node. Consulted on 7 October 2026.

Written by Bart van Engelenhoven Founder of Uniekaiconsultancy in Ede, the Netherlands. Bart analyses how SMEs work and builds software, integrations and AI applications himself. Last updated: 7 October 2026

Curious what could work for you?

The first conversation is free and without obligation
By phone or at your premises
You speak directly with me

Bart van Engelenhoven You tell me what takes up your time, I tell you honestly whether I can help.

Book a call +31 6 42 57 52 81