Short definition

Webhook — an HTTP request that a system automatically sends to a preconfigured URL when a specific event occurs.

Also known as: HTTP callback, event webhook.

A webhook sends an HTTP request from one system to another. Instead of repeatedly checking for changes, the source sends the request as soon as an event happens.

How does a webhook work?

You register a URL with the sending system. When an event occurs, such as a successful payment, a form submission, or a published article, the system sends an HTTP request with the details to that URL. The receiving system verifies the request, processes it, and responds with a status code.

What does this mean for a small business?

Webhooks can send new orders to accounting software, leads to a CRM, or form submissions to an inbox without repeated polling or manual updates. The receiving system must be robust because requests may be duplicated, arrive out of order, or be forged.

What should you watch for in a webhook?

  • verify signatures before processing anything;
  • make processing idempotent so retries do not repeat the effect;
  • respond quickly and process long-running work asynchronously;
  • log failed deliveries and provide a retry or reconciliation mechanism;

How it relates to other website choices

A webhook is often the push alternative to polling an API. Together, they support workflow automation and controlled integrations with AI agents.

Reliable source and further reading

For the technical foundation, read MDN on webhooks.