Architecture

Zero-trust architecture has become essential for modern application security, operating on the principle “never trust, always verify.” Unlike traditional perimeter-based security, zero-trust assumes no implicit trust based on network location and continuously validates every transaction. Understanding Zero-Trust Principles Zero-trust architecture is built on three core principles that fundamentally change how we approach security: Core Principles Verify Explicitly: Always authenticate and authorize based on all available data points Use Least Privilege Access: Limit user access to only what’s necessary Assume Breach: Minimize blast radius and segment access Traditional vs Zero-Trust Security | Aspect | Traditional Security | Zero-Trust Security | | ...

Traditional CRUD-based systems lose information. When you update a database record, the previous state is gone. In financial systems, this is unacceptable. Regulators require a complete audit trail. Accountants need to know the state of a transaction at any point in time. Dispute resolution requires reconstructing what happened, not just what the current state is. Event sourcing stores every change to system state as an immutable event. The current state is derived by replaying events. The full history is preserved by definition. For financial systems, event sourcing is not an architectural preference — it is a compliance requirement. ...

Processing payments at scale is one of the hardest problems in distributed systems. Every transaction must be exactly-once, the system must be available 99.999% of the time, and reconciliation must be perfect. A payment gateway that processes 100 million transactions per month cannot afford to lose a single transaction or double-charge a single customer. We have built payment gateway infrastructure for fintechs processing over $10 billion in annual transaction volume. The architecture decisions that matter are not about speed — they are about correctness, idempotency, and the ability to recover from partial failures without losing money. ...