The problem
Prime Peptides LLC is a high-risk merchant on Wix, and standard processors like Stripe and PayPal simply weren't available to them because of the industry they're in. That meant a non-standard, resilient payment architecture was the only real option. The checkout itself needed to dynamically inject a 5% processing fee, handle Wix promo codes, and manage shipping costs within the API payload without breaking price checksums in the process. And because the gateway runs on a crypto on-ramp through Simplex and Banxa, payments take 15 to 20 minutes to verify on-chain, which meant Wix order statuses needed to update accurately and automatically, with no manual intervention and no risk of data loss during that window.
What I built
A custom "Service Provider" integration bridging Wix and PsiFi
I built the integration using Wix Velo and Node.js, engineering a bridge between Wix E-commerce and the PsiFi/Simplex ecosystem so customers could pay by credit card through a crypto on-ramp seamlessly, keeping the business running in a market most standard gateways won't touch.
Dynamic payload engineering
I built a logic engine that decomposes the Wix cart, calculates the 5% gateway fee, and reassembles everything into PsiFi "Products" via API, all without breaking the price checksums that would otherwise flag the transaction as invalid.
Secure webhook architecture
I developed a backend listener (_functions/psifiWebhook) using HMAC-SHA256 signature verification, so only legitimate payment signals from PsiFi can actually update the database, closing off a path that would otherwise be wide open to spoofed confirmations.
Data synchronization that keeps the dashboard usable
I injected Wix buyer metadata, name, email, phone, along with order IDs, directly into the gateway session, so the merchant's dashboard stays organized and searchable instead of a disconnected list of anonymous transactions.
Idempotency and race-condition protection
I implemented unique cryptographic hashes for every line item to prevent duplicate charges and make sure "Order Completion" only ever triggers once, even with an asynchronous, 15-to-20-minute confirmation window in play.
What actually changed
| What changed | Before | After |
|---|---|---|
| Payment processing | Unavailable through standard gateways | Live, secure credit-card-via-crypto-on-ramp checkout |
| Order management | Manual reconciliation | Automated webhook-to-order sync, 100% reduction in manual management time |
| Fee handling | N/A | Dynamic 5% fee calculated without breaking price checksums |
| Security | N/A | HMAC-SHA256 verified webhooks, idempotent charge protection |
The result
The integration let the merchant go live and process credit card transactions securely despite the industry restrictions working against them. Automating the webhook-to-order flow cut manual order management time by 100%, delivering a checkout experience that feels like a standard credit card processor even with real crypto infrastructure running underneath it.