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I'm Zain Ul Abidin, a Senior Full Stack Engineer with 4+ years of experience architecting and shipping production-grade web applications across healthcare, compliance, and e-commerce. I specialize in Node.js, React, Vue, Angular, Ruby on Rails, and AWS, designing event-driven and distributed systems that deliver measurable performance gains. I work across the full stack from cloud infrastructure to client-facing APIs, with hands-on proficiency in PostgreSQL, Redis, Docker, CI/CD, and AI-assisted development tools including Cursor, GitHub Copilot, and Claude Code. I’m a collaborative problem-solver who loves turning complex requirements into reliable, scalable software.…I'm Zain Ul Abidin, a Senior Full Stack Engineer with 4+ years of experience architecting and shipping production-grade web applications across healthcare, compliance, and e-commerce. I specialize in Node.js, React, Vue, Angular, Ruby on Rails, and AWS, designing event-driven and distributed systems that deliver measurable performance gains. I work across the full stack from cloud infrastructure to client-facing APIs, with hands-on proficiency in PostgreSQL, Redis, Docker, CI/CD, and AI-assisted development tools including Cursor, GitHub Copilot, and Claude Code. I’m a collaborative problem-solver who loves turning complex requirements into reliable, scalable software.

Zain Ul Abidin Sr.

Full Stack Developer, Web Developer, Front-End Developer, +2

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I'm Zain Ul Abidin, a Senior Full Stack Engineer with 4+ years of experience architecting and shipping production-grade web applications across healthcare, compliance, and e-commerce. I specialize in Node.js, React, Vue, Angular, Ruby on Rails, and AWS, designing event-driven and distributed systems that deliver measurable performance gains. I work across the full stack from cloud infrastructure to client-facing APIs, with hands-on proficiency in PostgreSQL, Redis, Docker, CI/CD, and AI-assisted development tools including Cursor, GitHub Copilot, and Claude Code. I’m a collaborative problem-solver who loves turning complex requirements into reliable, scalable software.…I'm Zain Ul Abidin, a Senior Full Stack Engineer with 4+ years of experience architecting and shipping production-grade web applications across healthcare, compliance, and e-commerce. I specialize in Node.js, React, Vue, Angular, Ruby on Rails, and AWS, designing event-driven and distributed systems that deliver measurable performance gains. I work across the full stack from cloud infrastructure to client-facing APIs, with hands-on proficiency in PostgreSQL, Redis, Docker, CI/CD, and AI-assisted development tools including Cursor, GitHub Copilot, and Claude Code. I’m a collaborative problem-solver who loves turning complex requirements into reliable, scalable software.

Available to hire

I’m Zain Ul Abidin, a Senior Full Stack Engineer with 4+ years of experience architecting and shipping production-grade web applications across healthcare, compliance, and e-commerce. I specialize in Node.js, React, Vue, Angular, Ruby on Rails, and AWS, designing event-driven and distributed systems that deliver measurable performance gains.

I work across the full stack from cloud infrastructure to client-facing APIs, with hands-on proficiency in PostgreSQL, Redis, Docker, CI/CD, and AI-assisted development tools including Cursor, GitHub Copilot, and Claude Code. I’m a collaborative problem-solver who loves turning complex requirements into reliable, scalable software.

Skills

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Expert

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Language

Javanese

Advanced

Work Experience

Sr. Full Stack Developer at SentryKit

February 1, 2025 - Present

Architected a multi-tenant Amazon Seller intelligence platform, designing the full system to monitor buybox status, pricing, inventory, and financials across multiple marketplaces per tenant with no single points of failure. Built a real-time event-driven pipeline using Amazon SP-API, SQS, and Lambda to process ANY OFFER CHANGED events, extracting buybox ownership, price gaps, seller count, and Prime status with sub-second latency. Implemented an async two-phase report polling system with Sidekiq to eliminate thread-blocking across hundreds of concurrent tenants. Managed full AWS production infrastructure including ECS (Fargate), RDS PostgreSQL, ElastiCache, ECR, S3, SQS, and Lambda. Delivered Stripe billing, OAuth integration for SP-API, and a watchdog alert engine; designed Zapier alert integration and structured payloads for downstream automation.

Full Stack Developer at Complyos

June 1, 2023 - January 31, 2025

Led migration of Webpack v3 to v5 and Vue 2 to Vue 3 with LTS Node.js upgrade, modernizing frontend stack and improving build performance. Built automated PDF generation with Grover and Sidekiq for compliant document workflows. Streamlined deployments on Azure cloud infrastructure and Docker, ensuring consistent environments and faster release cycles. Developed and documented RESTful APIs with Swagger, powering multiple client-facing applications with clear, versioned contracts. Integrated ElasticSearch, reducing average page load time by 60% and boosting user engagement by 30%. Implemented real-time healthcare resource allocation with Node and WebRTC to handle heavy concurrent traffic.

Full Stack Developer at Biomark

March 1, 2022 - April 30, 2023

Led migration of core applications from Rails 5 to 7 and integrated Cloudflare and OmniAuth (OAuth), improving security, performance, and user trust. Automated data import workflows and third-party API integrations, reducing manual effort and streamlining reporting pipelines. Established frontend testing practices with Jest and Cypress, improving coverage and reducing production bugs. Implemented multi-tenant data access patterns and integrated AWS S3 for document storage.