< Payment gateway />
Full payment gateway built from scratch: the Vennox Pay case study
A full payment gateway: Pix, seller KYC, payouts, checkout and an API with webhooks.
Client context
Vennox Pay is the payment gateway VTA built from scratch. A seller opens an account, goes through KYC, registers products, creates payment links or integrates through the API, gets paid by Pix (Brazil's instant payment rail), card and boleto, and withdraws the balance from the dashboard.
This is the project that put VTA on both sides of the payments webhook. Besides integrating third party gateways (Stripe, Mercado Pago, BuckPay, Cakto and Paradise), the team knows what happens on the side that processes the payment.
The problem
A payment gateway is the kind of system where every bug costs real money: a payment confirmed twice, a payout released before settlement, a webhook the client never received. The foundation has to be predictable before it gets to be pretty.
The scope was the whole thing: seller onboarding with identity verification, processing for Pix, card and boleto, available and pending balance, payouts, hosted checkout, payment links and a public API with webhooks for integrators.
What we built
01
Seller onboarding and KYC
Company registration, document upload and approval before the account can operate. A seller only moves money after being verified.
02
Pix, card and boleto processing
Products, payment links and hosted checkout, with the split by payment method visible on the dashboard.
03
Balance, settlement and payouts
Available balance, pending balance, payout requests and financial history. The seller knows what can be withdrawn today and what is still settling.
04
Public API and webhooks
API keys, payment events delivered by webhook and an integrations panel. An integrator gets the confirmation in their own system without checking a statement.
05
Seller dashboard
Gross revenue, average ticket, transactions, recent sales with status, notifications and a light or dark theme. The screen the seller opens every day.
Stack, and why each piece
- Encore.ts
- TypeScript backend framework with typed services, infrastructure declared in code and built-in observability.
- Neon Postgres
- Managed serverless Postgres, with database branches for test environments.
- Next.js
- Seller dashboard and checkout.
- Fly.io
- Hosting for the backend services, in containers.
Questions about this project
Do you integrate my system with a gateway, or build a gateway from scratch?
Both. For most companies, integrating an existing gateway is the right call: faster, and you do not carry the payment operation yourself. Building your own makes sense when you process payments for third parties, as Vennox does. We help you decide before we quote.
How do you prevent duplicate payments and lost webhooks?
Idempotency on every event, retries with a record of what was delivered, and reconciliation between what the gateway reports and what the bank shows. That is what we learned building the processing side.
What does a payment integration cost?
It depends on the gateway, the methods (Pix, card, boleto) and what your system has to do after the payment. We do not publish a price list: every project gets a fixed quote within 24 hours.
Do you handle subscriptions and recurring billing?
Yes, by card and by Pix, depending on what the chosen gateway supports. Subscriptions, retries and cancellations are part of the scope from day one.
How long does a payment integration take?
Most projects ship in 1 to 15 days, with the sandbox tested before anything goes to production. The exact date comes with the quote.
Related service
Payment Gateway Integration Services
Also part of this kind of project
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