> ## Documentation Index
> Fetch the complete documentation index at: https://docs.unseen.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# Webhooks overview

> Why webhooks matter, signature verification, and event handling tips for Unseen Pay.

The SDK already exposes [`unseen.webhooks.verify`](/sdk/server/webhooks-verify). This page pulls back to **operational discipline**: retries, duplicates, secrets, and headers.

See [Express integration](/guides/webhooks-express) for raw-body middleware patterns.

## Headers

Expect `X-Unseen-Signature` with a hexadecimal HMAC digest of the **raw POST body**.

## Operational guidance

Handle duplicate deliveries idempotently (Unseen may retry HTTP 5xx or timeouts).

Store and compare `paymentId`, `reference`, or event IDs before committing inventory.

**Next:** [React SDK — Installation](/sdk/react/installation) once the backend path—from session creation through signed webhooks—is clear.