Webhooks

Webhooks are HTTP callbacks sent from PayIn to a merchant system when payment events occur.

They are the usual way for merchant software to learn that an order was paid, a deposit was detected, or a payment status changed.

Common events

Examples include:

• Order created
• Payment pending confirmation
• Payment confirmed
• Order expired
• Deposit detected
• Webhook delivery failed or retried

Integration requirements

A production webhook endpoint should:

1. Accept HTTPS requests.
2. Verify webhook signatures.
3. Return a success status quickly.
4. Process events idempotently.
5. Store event IDs to avoid duplicate side effects.
6. Retry internal business processing separately when needed.

Why idempotency matters

Webhook delivery can be retried. A merchant system must safely handle the same payment event more than once without double-crediting a user or fulfilling an order twice.