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Paymish Payment Gateway

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Role: Full-Stack & Systems Architect

Paymish stands as a secure, fast, and reliable digital payment gateway catering exclusively to modern businesses seeking low lag checkouts. It orchestrates complex multi-bank API flows using Node.js microservices.

Technologies Used

Node.jsExpressPostgreSQLSocket.ioMicroservicesAxiosTypeORMBank APIs integrationSESTwilioS3firebase

Key Challenges

  • !Minimizing internal latency down to milliseconds to beat timeout windows on Bank APIs.
  • !Architecting an infrastructure capable of scaling infinitely under sudden traffic bursts.
  • !Applying rigorous security limits to stop fraudulent exploitation.

Solutions & Execution

  • Used isolated Node.js microservices so high-computation jobs don't block critical socket connections.
  • Tightly integrated TypeORM with an enterprise-grade PostgreSQL instance to enforce data security via schemas.
  • Developed custom IP tracking and rate-limiting modules via Redis to intercept malicious bot activities.

Project Highlights

  • Enterprise-grade security controls
  • Near-instant transaction parsing via optimized queues
  • Seamless bank-layer integrations

Impact & Results

Processing $2M+ in transactions monthly with 99.99% uptime
Reduced transaction latency to under 200ms average
Blocked 10,000+ fraudulent attempts through intelligent rate limiting
Achieved PCI DSS Level 1 compliance for payment security

Technical Deep Dive

Paymish's microservices architecture runs on Node.js with Express, where each service handles a specific domain—transaction processing, fraud detection, bank API communication, and settlement reconciliation. PostgreSQL with TypeORM provides ACID transaction guarantees, crucial for financial operations where every cent must be tracked. We implemented Redis-based distributed rate limiting across microservices, using sliding window counters to prevent abuse while allowing legitimate high-volume merchants. Bank API integrations use circuit breakers that automatically fall back to backup payment routes when primary channels fail. The system logs every transaction attempt with cryptographic signatures for audit trails, storing sensitive cardholder data in encrypted vaults separate from transactional databases. Real-time fraud detection analyzes transaction patterns using rule engines, flagging suspicious activity before money moves.

User Benefits

Businesses get a payment gateway that actually works when they need it most—during high-traffic sales and promotional periods. The dashboard provides real-time transaction visibility, automated reconciliation with bank statements, and detailed analytics on payment success rates. Customers experience lightning-fast checkout with support for all major payment methods, reducing cart abandonment rates. The system automatically retries failed transactions through alternate payment channels, recovering revenue that would otherwise be lost. Multi-currency support and instant settlement options help businesses expand internationally without payment infrastructure headaches.

Key Lessons Learned

Building payment infrastructure taught us that security cannot be an afterthought—it must be architected into every layer from day one. We learned to design for idempotency religiously; duplicate payment submissions must never charge customers twice. Bank API integration showed us the importance of comprehensive monitoring and alerting—payment failures cascade quickly, so early detection is critical. The biggest challenge was balancing fraud prevention with user experience—too strict and legitimate transactions get blocked, too loose and fraud increases. We solved this with adaptive risk scoring that learns from historical patterns.