Chadjaa Sofiane

I’m a Full Stack Engineer with 5+ years of experience building scalable web applications, real-time systems, and high-performance APIs. I’m known for reducing latency, optimizing data-heavy applications, and designing reliable system architectures across fintech and SaaS environments.

At 3S-Pay (FinTech), I designed and delivered 200+ REST and GraphQL API endpoints using Node.js, Bun, and Express for high-volume fintech transaction workflows. I built real-time infrastructure with Server-Sent Events, Socket.IO, and MQTT to connect and manage 1,000+ payment terminals.

I also strengthened identity and security by integrating Keycloak and OAuth2/OIDC, and I developed Java-based microservices for high-throughput token validation. To improve performance, I implemented Redis caching layers that reduced database load by 90% and cut API response times from 350ms to 45ms, while automating infrastructure provisioning with Docker, Nginx, and SSL/TLS.

Before that, I contributed as a Front-End Developer at DataMaster, building dashboards that render and interact with 10,000+ row datasets using React Table with row virtualization, and improving Core Web Vitals and WCAG compliance. As a Freelance Full Stack Developer, I delivered full-stack applications for startups and SMBs using React, Vue.js, Node.js, and Django REST, writing Jest/React Testing Library tests to reduce regressions and stabilize releases.