Webhook handling for reliable fulfillment
Verify signatures, handle retries, and update order state only after Outpay confirms a matching on-chain payment.
Implementation preview
const signature = request.headers.get("X-Outpay-Signature");
const verified = verifyOutpaySignature(rawBody, signature, webhookSecret);
if (verified && event.event === "checkout.paid") {
await fulfillOrder(event.checkout_id);
}HMAC
verification
Retry
delivery model
Paid
fulfillment event
Server-side first, checkout last
Verify first
Check the X-Outpay-Signature header before trusting the payload or updating your database.
Fulfill once
Store processed event or checkout IDs so repeated deliveries do not duplicate shipments.
Monitor delivery
Use dashboard logs to inspect response codes and fix endpoint failures quickly.
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.
const signature = request.headers.get("X-Outpay-Signature");
const verified = verifyOutpaySignature(rawBody, signature, webhookSecret);
if (verified && event.event === "checkout.paid") {
await fulfillOrder(event.checkout_id);
}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.