Hey there, I'm Nilava Chowdhury

   

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@@ Engineering Leader | Government Tech Specialist | Scale Architect @@
+ Built India's FIRST Wallet-Based Metro Card (Google Wallet Certified)
+ Architected Systems Processing 10M+ Daily Transactions
+ Led Pan-India Metro Digital Infrastructure (Mumbai, Hyderabad, Pune, Nagpur)
+ 150 TPS Flash Sale Architecture | 99.99% SLA Uptime
! "From Fitness Apps to National Transit Systems - I Build at Scale"

🚀 About Me

javascript
const nilava = {
    currentRole: "Head of Engineering @ Billeasy",
    previousRoles: ["Tech Lead @ udChalo", "Software Engineer @ StepSetGo"],
    experience: "5+ years building mission-critical systems",
    
    expertise: {
        scale: ["10M+ daily transactions", "150 TPS systems", "99.99% SLA"],
        mobile: ["React Native", "iOS/Android Native", "100K+ downloads"],
        backend: ["Microservices", "Kubernetes", "Node.js", "gRPC"],
        infrastructure: ["AWS/GCP", "Docker", "Kafka", "Redis", "PostgreSQL"],
        security: ["SSL Pinning", "PCI Compliance", "Cryptographic Systems"],
        payments: ["Google Wallet NFC", "UPI", "Payment Gateways"]
    },
    
    achievements: {
        "🚇": "Built India's FIRST wallet-based metro card with Google",
        "🎫": "Deployed QR ticketing for 4 major metros (CDAC compliant)",
        "🚢": "Architected complete AFC system for Maharashtra ferries",
        "✈️": "Launched udChalo app - 100K downloads in 6 months",
        "🏃": "Led fitness vertical processing millions of steps daily",
        "🔒": "Zero security breaches across all platforms"
    },
    
    partnerships: ["Google Wallet Certified", "Meta WhatsApp Business", "Government of India"],
    
    philosophy: "Build systems that scale to millions, not thousands"
};

🏛️ Government & Enterprise Impact

• 🚇 Metro Networks: Architecting digital infrastructure for Mumbai, Hyderabad, Pune, Nagpur metros
• 🚢 Maritime Board: Complete ticketing solution for Maharashtra ferry network
• ✈️ Armed Forces: Built mobile platform serving 100K+ defense personnel
• 🍔 Enterprise: Scaled Tim Hortons & Belgian Waffle for national flash sales

🏆 Career Highlights & Impact

🚀 Nation-Scale Projects I've Built

Billeasy - Head of Engineering

• 🏆 India's First NFC Metro Card: Pioneered wallet-based metro card with Google Wallet integration using NXP MIFARE standards - Set National Benchmark for digital fare collection
• 🚇 Pan-India Metro Infrastructure: Deployed CDAC-compliant QR ticketing across Mumbai, Hyderabad, Pune, Nagpur metros - Millions of daily rides with 99.99% uptime
• 🚢 Maharashtra Ferry System: Built complete AFC system with WhatsApp ticketing & operator apps - Entire state network digitized
• ⚡ Enterprise Flash Sales: Migrated monolith to microservices for Belgian Waffle & Tim Hortons - 150 TPS on National Waffle Day

udChalo - Technical Team Lead

• ✈️ Defense Personnel App: Led complete mobile app development for armed forces flight booking - 100K+ downloads, 4.5★ rating in 6 months

StepSetGo - Software Engineer

• 🏃 Fitness Ecosystem: Built native modules & integrated 15+ wearable devices - 10M+ daily events, 98% accuracy
• 🔒 Security Infrastructure: Implemented SSL pinning, PCI compliance, fraud detection - Zero breaches, 90% fraud reduction

🎖️ Technical Leadership Metrics

• Team Size: Led cross-functional teams of 15+ engineers
• User Scale: Systems serving millions of daily active users
• Transaction Volume: 10M+ daily transactions across platforms
• Availability: Maintained 99.99% SLA for critical infrastructure
• Partnerships: Google Wallet, Meta WhatsApp, Government of India
• Cost Optimization: Reduced infrastructure costs by 40% through optimization

💻 Tech Stack & Architecture Expertise

🏗️ System Architecture

!Microservices !Event Driven !Serverless !gRPC !GraphQL

📱 Mobile & Frontend

!React Native !Swift !Kotlin !TypeScript !React

⚙️ Backend & Infrastructure

!Node.js !Kubernetes !Docker !AWS !GCP

🔄 Data & Messaging

!Kafka !Redis !PostgreSQL !MongoDB !RabbitMQ

🛡️ Security & Compliance

!OAuth !JWT !SSL/TLS !PCI DSS !CDAC

📊 Monitoring & DevOps

!Prometheus !Grafana !ELK Stack !Istio !ArgoCD

💼 Professional Journey

mermaid
graph LR
    A[2020: Application DeveloperStepSetGo] --> B[2021: Software EngineerStepSetGo]
    B --> C[2024: Technical Team LeadudChalo]
    C --> D[2025: Head of EngineeringBilleasy]
    
    style A fill:#f9f,stroke:#333,stroke-width:2px
    style B fill:#bbf,stroke:#333,stroke-width:2px
    style C fill:#9cf,stroke:#333,stroke-width:2px
    style D fill:#9f9,stroke:#333,stroke-width:2px

📈 Career Progression

• 🏢 Billeasy _(Current)_ - Head of Engineering - Building nation-scale transit infrastructure
• 🏢 udChalo _(1 Year 6 months)_ - Tech Lead - Launched defense personnel app (100K+ users)
• 🏢 StepSetGo _(3+ years)_ - Software Engineer - Scaled fitness platform to millions

💪 Core Competencies & Expertise

🏗️ Architecture & Scale

• Expertise: Kubernetes, Microservices, Event-Driven, gRPC
• Real-World: Built systems handling 10M+ daily transactions

📱 Mobile Development

• Expertise: React Native, Swift, Kotlin, Native Modules
• Real-World: 100K+ app downloads, 4.5+ star ratings

☁️ Cloud & DevOps

• Expertise: AWS, GCP, Docker, Istio, ArgoCD, Helm
• Real-World: 99.99% uptime on critical infrastructure

🔒 Security & Compliance

• Expertise: SSL Pinning, PCI DSS, CDAC, Cryptography
• Real-World: Zero security breaches across all platforms

💳 Payment Systems

• Expertise: Google Wallet NFC, UPI, Payment Gateways
• Real-World: India's first wallet-based metro card

📊 Data Engineering

• Expertise: Kafka, Redis, PostgreSQL, Sharding
• Real-World: 150 TPS flash sale architecture

👥 Leadership

• Expertise: Team Management, Stakeholder Management, Mentoring
• Real-World: Led teams of 15+ engineers on government projects

📊 GitHub Analytics & Activity

🏆 GitHub Trophies

🐍 Contribution Snake

📈 Activity Graph

📊 Profile Summary


🏗️ Featured Projects

 

📈 3D Contribution Calendar


🏅 Certifications & Partnerships

🎖️ Official Certifications

• 🔵 Google Wallet Partner - Certified for closed-loop Tap & Pay NFC implementation
• 🟢 WhatsApp Business API - Official Meta partner for transit ticketing integration
• 🇮🇳 CDAC Compliance - Government of India QR ticketing infrastructure certification
• ☁️ AWS Solutions Architect - Cloud architecture and scalability certification
• 🔒 PCI DSS Compliance - Payment card industry data security standards

🎯 Current Focus & Initiatives

🔭 Leading At Scale

!Metro Infrastructure !Government Projects !10M+ Daily Transactions

Current Initiatives:

• 🚇 Pan-India Metro Digital Expansion
• 🎫 Next-Gen NFC Payment Systems
• 📊 Real-time Transit Analytics Platform

🌱 Exploring Next

!Web3 Payments !AI/ML Integration !IoT Transit

Research Areas:

• 🤖 AI-powered fraud detection systems
• 🔗 Blockchain for secure ticketing
• 📡 IoT sensor networks for crowd management

📊 Weekly Development Breakdown

<!--START_SECTION:waka-->

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React Native     ████████████░░░░░░   48.2%
TypeScript       ██████░░░░░░░░░░░░   25.7%
JavaScript       ████░░░░░░░░░░░░░░   16.3%
Swift            ██░░░░░░░░░░░░░░░░    8.2%
Other            ░░░░░░░░░░░░░░░░░░    1.6%

<!--END_SECTION:waka-->

🏛️ Notable Clients & Projects

Government & Public Sector

Enterprise Partners

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📝 Technical Articles & Thought Leadership

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• 🚇 [Building India's First NFC Metro Card: A Technical Dee

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