How it works
You register a URL and choose the events you care about, such as invoice created or order fulfilled. When the event happens, the sender makes a POST request to your URL with a JSON payload describing it. Good webhook systems sign each request so you can verify the sender, retry with backoff when your endpoint is down, and include an event id so you can ignore duplicates.
Example
An AP product subscribes to bill events. When a customer approves a bill in NetSuite, the product receives a webhook within moments and schedules the payment, instead of checking every bill every fifteen minutes.
In integrations
Many platforms either lack webhooks or send them inconsistently. Unify Sync is designed to emit one signed webhook format for changes on the Unify Graph, generated from native webhooks where a platform has them and from change detection where it does not. Unify Monitor logs every delivery and lets you replay events to your endpoint. Webhooks matter because polling every customer's account on a timer wastes rate limits and still leaves you minutes behind. Treat them as at-least-once delivery: verify the signature, store the event id and make handlers safe to run twice.