Payment Processing Simulation API®
intro
This project simulates the complete payment processing lifecycle — authorization, capture, refund and void — built with Java and Spring Boot.
The API was designed with PCI compliance in mind: no full PAN storage, tokenized card references, and an append-only audit log for complete transaction traceability.
Key features include JWT-based merchant authentication, Redis-powered rate limiting, and idempotency keys to prevent duplicate transactions in distributed environments.
client
Personal Project
service
Java & Spring Backend
sector
Fintech & Payments
year
2025
insights
A key insight from this project was the importance of designing financial systems with security and auditability as first-class concerns, not afterthoughts.
The PCI-aware architecture ensures sensitive card data is never stored in full, while the append-only audit log provides complete transaction history for compliance and debugging.
Redis-based rate limiting and idempotency keys proved essential for building a resilient API that handles concurrent requests safely in production-like conditions.
Outro
This project demonstrates end-to-end backend engineering skills: secure API design, transaction state management, caching strategies and compliance-aware architecture — all built following enterprise development standards.
Credits
César Intriago
Backend Developer