Sagnik Nandy

Full Stack & Mobile Developer with 3.5+ years of experience building scalable SaaS platforms and cross-platform applications. Skilled in React, Node.js, and FastAPI, with practical experience in AI system development using LangChain and LangGraph. Proven ability to design, develop, and deploy production-grade applications with real-time systems, authentication, payments, and cloud deployment.

Full Stack Developer - IQBook - United Kingdom, Remote

(2023-03)

SaaS Salon Management Ecosystem

• Architected a multi-tenant SaaS platform serving thousands of active web users, featuring a high-performance Admin Dashboard and a dedicated mobile interface.
• Crafted a secure payment infrastructure using Stripe, implementing asynchronous Webhooks to manage subscription lifecycles with 100% transactional integrity.
• Pioneered a real-time synchronization engine using WebSockets, delivering instantaneous updates for live queue statuses and appointments.
• Enforced a robust Security framework using Google OAuth 2.0 and JWT, engineering custom middleware for backend route protection.
• Designed a scalable NoSQL architecture in MongoDB, utilizing advanced document embedding to manage complex relations across multi-location salons.
• Orchestrated geospatial features via Google Maps API, enabling location-based discovery for a seamless client booking experience.
• Deployed a unified notification engine leveraging Firebase Cloud Messaging (FCM) to facilitate background push notifications for persistent engagement.
• Managed full-stack deployment using Netlify and Render.com with GitHub CI/CD, integrating Cloudinary and the Twilio API.

React Native Developer - IQBook - United Kingdom, Remote

(2024-01)

IQBook Customer Mobile Application

• Architecting a high-performance rebuild and modernization of a large-scale customer application using React Native and Expo, migrating legacy systems while integrating new high-concurrency features to serve 50,000+ active users.
• Engineered a sophisticated Multi-Mode Queuing System, utilizing Redux for complex real-time state management across high-concurrency sessions.
• Integrated an automated booking engine with dual-synchronization for Google Calendar and Local Device Calendars.
• Collaborated with Google Maps API and a secure Stripe payment gateway to facilitate seamless in-app transactions.
• Built a comprehensive Identity Management system featuring OTP verification and Firebase-driven Push Notifications.
• Optimized the application for 100% responsiveness, managing the end-to-end Deployment to the App Store and Play Store.

Bachelor of Science - Science - Kanchrapara College