A self-hosted checkout that connects Zoho Books, Paytrace, and InterPayments — so the client could legally recover card fees and reconcile every payment automatically.
The project
The client was losing real money to credit card processing fees and wanted to pass them on as a surcharge — but surcharging is regulated differently in every state, and getting it wrong creates compliance risk. On top of that, payments needed to stay perfectly in sync with their Zoho Books invoicing.
We built a self-hosted payment system that handles all of it: it checks surcharge legality in real time, reduces PCI scope by using hosted checkout, keeps the client's branding through a custom pre-checkout page, and reconciles every payment back to the right invoice automatically.
How it works
The backend fetches live invoice details straight from Zoho Books.
InterPayments determines whether a surcharge is allowed in that state.
A Paytrace hosted checkout link is created behind a custom pre-checkout page.
The webhook marks the invoice paid in Zoho and logs the decision for audit.
What we built
Hosted on the client's own domain, showing the invoice total plus any calculated surcharge — fully on-brand, so customers never feel handed off to a third party.
Fetches invoices from Zoho, checks surcharge legality with InterPayments, generates Paytrace checkout links, and handles every webhook response.
Paytrace payments are matched back to the correct Zoho invoice and marked paid automatically — no manual bookkeeping, no mismatched records.
Every InterPayments surcharge decision is recorded with a traceable payment history — so the client can prove compliance during any audit.
Nuxt, Django Ninja, and PostgreSQL containerized with Docker Compose, deployed to the client's DigitalOcean infrastructure with SSL, monitoring, and automated backups.
By routing card entry through Paytrace's hosted checkout, sensitive card data never touches the client's servers — keeping their PCI compliance burden low.
The result
The client now recovers credit card fees where it's legal to do so, keeps their books reconciled without manual work, and runs the entire system on their own infrastructure — no per-transaction SaaS markup, no vendor lock-in.
Because it's self-hosted and cleanly architected, it's theirs to keep and extend. We shipped it in eight weeks with 30 days of post-launch support.
We connect the tools you already use into something that just works — on your infrastructure, on your terms. Tell us what you need.