Webhooks Explained

A webhook is a message a system sends the moment something happens, so other systems react immediately instead of asking repeatedly.

What is a webhook?

A webhook is an automatic message one system sends to another the moment an event happens — a payment received, a document signed, a job completed. Instead of repeatedly asking whether anything changed, the receiving system is told immediately, which is what makes real-time automation possible.

Key takeaways

An API call asks. A webhook tells.
Webhooks make automation react in seconds, not minutes.
They must be verified, or anyone could fake the event.
Delivery can retry, so handlers must tolerate duplicates.

Polling versus pushing

Polling means asking every minute whether something changed — wasteful, slow, and usually late. A webhook pushes: when the event occurs, the source system immediately sends a small message describing it.

This is why a signed contract can trigger an invoice within seconds rather than on the next scheduled sync.

What has to be handled correctly

Verify the signature so forged events are rejected.
Respond quickly, then process the work in the background.
Expect duplicates and make handling idempotent.
Log every received event for troubleshooting and audit.

Frequently Asked Questions

Related knowledge

What Is an API?

Event-Driven Business Systems