Nawab Kibria

Full Stack Developer

Gcbuying • Part-time

May 2020 - Present • 6 yrs 6 mos

I work as a senior full-stack developer at GcBuying, where I play a key role in architecting, building, and scaling a high-traffic B2B2C crypto and digital gift card trading platform serving 100,000+ users. My responsibilities include leading the end-to-end development of web and mobile applications, migrating the platform from a Laravel monolith to a NestJS-based microservices architecture, and designing secure, scalable backend systems. I built and maintained multi-chain custodial wallet infrastructure in-house, replacing third-party payment and crypto providers while ensuring high security, reliability, and regulatory compliance. I actively work across backend, frontend, DevOps, and blockchain layers—implementing real-time systems, payment integrations, KYC workflows, CI/CD pipelines, and cloud-native deployments on AWS and GCP using Docker, Kubernetes, Terraform, and Vault. Key contributions: - Architected and developed 15+ NestJS microservices with MongoDB, Redis, RabbitMQ, and Kafka. - Built multi-currency crypto wallets (BTC, ETH, USDT, TRX, SOL, BNB, etc.) with real-time pricing and auto conversion - Led development of React, Next.js, and React Native applications (iOS & Android) - Implemented secure authentication, KYC verification, RBAC, and 2FA - Designed real-time features using WebSockets and background job processing - Managed CI/CD, infrastructure automation, and cloud deployments Served as the sole developer for core wallet and payment systems used by over 300K users This role combines technical leadership, system architecture, and hands-on engineering to deliver secure, scalable fintech and blockchain solutions.