Mint Rewards
High-Throughput Merchant Loyalty & Rewards Processing Platform.
“Led technical architecture for automated loyalty point calculation, merchant POS webhooks, and secure customer redemptions.”
Replace with high-res UI dashboard screenshot, mockup, or banner (Recommended 1920x1080)
Contract Technical Leadership for High-Volume Loyalty
Served as contract Technical Lead spearheading the architecture and engineering execution of Mint Rewards. Designed high-concurrency event pipelines processing real-time merchant transaction webhooks, point accruals, and fraud-resistant customer redemptions.
Project at a Glance
A scalable merchant loyalty and consumer rewards engine handling automated point accruals, tier upgrades, promotional campaigns, and secure reward redemptions.
Fintech Loyalty Platforms & High-Concurrency Transaction Processing
Merchant Networks & Consumer Brands
Contract Technical Lead Tenure
Processed high-volume retail transactions with zero balance discrepancies and sub-second points settlement.
The Problem
Merchant loyalty platforms face unpredictable transaction spikes during retail shopping hours. Point systems require absolute financial consistency: double-spends, race conditions in redemption, or dropped webhook events destroy trust between merchants and consumers.
Webhook burst traffic from merchant POS systems overwhelming standard web servers.
Concurrency race conditions causing users to double-spend rewards points.
Lack of unified multi-merchant ledger tracking points liability across brand partners.
Slow mobile checkout redemption causing checkout line delays in retail stores.
Goals
Technical Goals
- High-throughput webhook ingestion queue handling bursts of 5,000+ events/minute.
- ACID-compliant double-entry ledger ensuring points integrity across all accounts.
- Sub-200ms mobile redemption verification at point-of-sale checkout terminals.
- Idempotent event processing preventing duplicate point rewards from repeated webhooks.
Business Goals
- Increase customer repeat purchase rates across participating merchant networks.
- Provide merchants with real-time customer lifetime value (LTV) analytics.
- Eliminate customer support disputes regarding missing or miscalculated reward points.
My Role
Technical Lead (Contract)
Core Responsibilities
- Led engineering team across sprint planning, code reviews, and architectural alignment.
- Designed the event-driven queueing pipeline using Redis and message brokers.
- Architected the financial ledger database schema in PostgreSQL with row-level locks.
- Guided merchant integration engineers on POS webhook standards and authentication.
Primary Focus Areas
Solution
Architected an event-driven rewards platform. Inbound merchant purchase webhooks are received by a lightweight ingestion gateway, queued into Redis, and processed by transactional workers that update the customer's immutable points balance ledger with cryptographic idempotency keys.
Idempotent Webhook Gateway
Deduplicates incoming retail events and acknowledges receipt in under 20ms to prevent POS timeouts.
Double-Entry Points Ledger
Every point minted or burned corresponds to a debit/credit ledger row, preventing balance drifts.
Real-Time Merchant Dashboard
Live analytics tracking active customer participation, tier progressions, and promotional ROI.
Architecture & Data Flow
High-resilience architecture decoupling merchant webhook ingestion, event queue processing, PostgreSQL transactional storage, and mobile redemption APIs.
POS Webhook Ingestion
Node.js / Express GatewayMerchant registers customer purchase; POS sends webhook to Mint Rewards gateway.
Idempotency & Queueing
Redis / BullMQRedis validates idempotency key to reject duplicates and queues task for processing.
Transaction Ledger Execution
PostgreSQL Atomic DBWorker calculates points based on active tier rules and writes atomic ledger entry.
Customer & Merchant Sync
WebSockets / S3 ReportsUpdated balance pushes to mobile app via WebSocket; merchant analytics updated.
Core Features
Automated Rules Engine
Flexible campaign logicConfigurable promotional multipliers, bonus point days, and milestone achievements.
Instant QR POS Redemption
Sub-second checkout verificationGenerates dynamic, short-lived QR tokens scanned at retail checkout for immediate reward redemption.
Tiered Loyalty Status
Automated tier promotionsAutomatic progression between tiers (Silver, Gold, Platinum) based on rolling annual spend thresholds.
Auditable Financial Ledger
Zero balance discrepancyFull transactional auditability for financial reconciliation and merchant settlement billing.
Engineering Decisions
Asynchronous Queueing with Redis/BullMQ vs Direct Synchronous DB Writes
Why: Direct DB writes caused lock contention and server timeouts during peak Friday evening shopping rushes; queueing guaranteed 100% event capture without dropping webhooks.
Challenges
Concurrent Redemption Race Conditions: Customers attempting to scan identical coupon codes simultaneously on multiple devices.
Implemented database row-level locking (SELECT FOR UPDATE) combined with short-lived Redis distributed locks.
Completely eliminated double-redemption vulnerabilities.
Implementation Timeline
System Design & Financial Ledger
- Double-entry DB schema
- Idempotency protocol
- Core calculation library
Webhook Gateway & Workers
- BullMQ worker cluster
- POS webhook validation
- Tier evaluation engine
Web & Mobile Interfaces
- Merchant analytics dashboard
- Dynamic QR redemption module
- Admin ledger tools
Stress Testing & Merchant Rollout
- 10,000 req/min stress test
- POS pilot integration
- Production launch
Results & Metrics
Perfect financial balance reconciliation across millions of points transactions.
Ultra-fast response time ensuring zero timeout errors on merchant POS terminals.
Stress-tested throughput capacity during holiday flash sales.
Screenshots
Drop high-resolution interface screenshot here (Recommended 1920x1080)
Merchant Loyalty Campaign & Analytics Console
Merchant view tracking real-time loyalty member purchases, point accruals, and campaign ROI.
Drop high-resolution interface screenshot here (Recommended 1920x1080)
Customer Rewards Portal & QR Redemption Terminal
Mobile-friendly interface displaying available rewards and dynamic secure redemption tokens.
Demo Video
Mint Rewards Platform Demo: 2-minute video demonstrating POS webhook ingestion, instant points calculation, and mobile QR redemption.
Add iframe or video src in lib/case-studies-data.ts
Demonstration Highlights:
Lessons Learned
Financial and points engines must treat every balance modification as an immutable ledger transaction rather than mutating a simple counter column.
Idempotency keys on incoming webhooks are mandatory to survive real-world network retries without double-crediting.
Tech Stack
Backend & Queues
Database & Ledger
Frontend & Dashboards
Business Impact
Mint Rewards enabled retail brands to deploy enterprise-grade loyalty programs that boosted customer retention and lifetime value without infrastructure headaches.