Signed payment events for production fulfillment
Fulfill orders from server-side events after Outpay verifies the matching USDC transfer on Base.
Implementation preview
POST /webhooks/outpay
X-Outpay-Signature: t=..., v1=...
{
"event": "checkout.paid",
"checkout_id": "chk_9k2n",
"amount": "124.00",
"currency": "USDC"
}HMAC
signed events
Base
payment source
201
created checkout
Product capabilities
Signed checkout.paid events
Server-side fulfillment trigger
Retry-safe delivery model
Audit trail for webhook attempts
Built for operational trust, not manual crypto payment handling.
01
No fulfillment from browser redirects
02
No trusting unsigned payloads
03
No duplicated orders when retries happen
Server-side confidence
Your backend receives checkout.paid only after Outpay verifies the on-chain transfer.
Signature verification
Use the webhook secret to verify the payload came from Outpay before fulfilling an order.
Delivery observability
Track response codes and timestamps so failed deliveries are visible to your team.
Designed for backend-controlled checkout
Keep payment creation, webhook verification, and order fulfillment on your server. Customers only see the hosted checkout page and wallet payment request.
POST /webhooks/outpay
X-Outpay-Signature: t=..., v1=...
{
"event": "checkout.paid",
"checkout_id": "chk_9k2n",
"amount": "124.00",
"currency": "USDC"
}Ready to run USDC checkout like payment infrastructure?
Start with hosted checkout links, then add the API and webhooks when you want a deeper store integration.
Review pricing
Outpay© 2026 Outpay. Non-custodial checkout for USDC on Base.
Outpay is a non-custodial checkout and payment verification tool. Funds move directly from customer wallets to merchant wallets. Outpay does not hold, custody, convert, or settle customer funds.