Engineering Research
Exploring the architecture behind modern payment systems.
Payment infrastructure is fragmented, underdocumented, and harder to build correctly than almost any other domain in software. These articles document the structural problems — and what better architecture could look like.
Farnaz Bagheri · Software Engineer · Payment Infrastructure
Research Areas
POS System Integrations
How payment terminals communicate with backend services, EMV certification constraints, and the gap between SDK documentation and production behavior.
Processor Interoperability
Why payment processors expose inconsistent APIs for identical operations, and what a normalized abstraction layer would need to handle.
Transaction State Architecture
Modeling payment lifecycle as a state machine — from authorization to capture, void, and refund — across distributed, sometimes-offline systems.
Recent Writing
All articles →Tokenization Beyond PCI: Building a Secure Payment Vault
Most teams treat tokenization as a compliance mechanism — a way to shrink PCI scope. That's the minimum bar. A well-designed vault is a product capability, not a compliance cost, and the difference shows up in what your platform can do that competitors can't.
Building Payment Webhooks That Don't Lose Events
Webhooks look like the easy side of payment integration. They're an HTTP endpoint that receives notifications. What could go wrong? Almost everything, it turns out, and the failure modes are specific enough that most implementations have at least three of them.
When Payments Go Down: Incident Response for Financial Systems
Most incident response playbooks assume the worst outcome is downtime. In payment systems, downtime is the best-case scenario. The worst case is that the system keeps running while producing wrong results, and recovering from that is a completely different kind of work.
You Can't Fix What You Can't See: Observability in Payment Systems
Observability in most systems means knowing whether the system is up. Observability in payment systems means knowing whether the money is where it's supposed to be — and those are not the same question.
About
Software engineer focused on payment infrastructure — the backend architecture, device protocols, and integration patterns that underlie POS systems and fintech platforms. Writing toward a more coherent understanding of how payment systems should be designed.
More about me →- Stack
- Node.js · TypeScript · React · MongoDB
- Domain
- Payment Infrastructure · POS Systems
- Protocols
- EMV · ISO 8583 · REST