Webhook vs Callback: What's the Difference?
A callback is a function you hand to other code to be run later when something happens, inside a single program. A webhook is the same idea across the network: instead of calling a function in memory, a remote server sends an HTTP request to a URL you registered when an event happens. A webhook is often described as an HTTP callback or web callback, so the concepts are related, but a callback is in-process while a webhook crosses system boundaries over HTTP.
Webhook vs callback at a glance
| Webhook | Callback (in code) | |
|---|---|---|
| Where it runs | Across systems, over HTTP | Inside one program, in memory |
| Trigger | A remote event | A local event or completed operation |
| Mechanism | HTTP request to a registered URL | A function reference invoked later |
| Failure modes | Network errors, retries, security | Exceptions in the same process |
A note on "callback URL"
The term callback is sometimes used loosely to mean the URL a service redirects to, such as an OAuth callback. That is a browser redirect, not a webhook. A webhook is a server-to-server HTTP request carrying event data, not a user redirect.
How Hookdeck fits
Because a webhook is a callback that travels over the network, it inherits network problems a normal function call never has: the request can fail, duplicate, land out of order, or come from an unverified sender. Hookdeck's Event Gateway handles exactly those concerns, verifying signatures, retrying failures, and recording every delivery, so a webhook behaves as reliably as an in-process callback. See how it works, or catch live webhooks on your machine with the CLI.
Related questions
Webhook infrastructure, managed for you
Hookdeck handles ingestion, delivery, observability, and error recovery — so you don't have to.