Open to opportunities

J Jeff

@jjeff

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Senior Ruby on Rails engineer focused on scalable, high-concurrency web platforms and legacy modernization.

China

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What I'm looking for

I seek senior backend or technical-owner roles where I can design scalable systems, modernize legacy platforms, and collaborate across product and operations for measurable impact.

I am a seasoned Ruby on Rails engineer with over 10 years building production-grade web platforms across e-commerce, healthcare, government, hyperlocal services, and judicial systems.

I specialize in designing high-concurrency architectures, refactoring complex legacy monoliths, and delivering stable, maintainable systems that meet regulatory and operational requirements.

I frequently act as technical owner, managing requirement analysis, system design, stakeholder communication, and end-to-end delivery across startup and enterprise contexts.

Notable achievements include stabilizing systems to handle 4,000+ QPS during flash sales, delivering hospital-grade telemedicine integrations, and modernizing large public-sector procurement and court case platforms.

Experience

Work history, roles, and key accomplishments

Senior Ruby on Rails Engineer

Freelance / Independent Consultant

Nov 2022 - Jan 2025 (2 years 2 months)

Provided maintenance, optimization, and feature development for multiple business-critical production systems, improving stability and aligning technical changes with revenue needs across client platforms.

Ruby on Rails PostgreSQL Redis React Performance Optimization Sidekiq CI CD

Senior Ruby on Rails Engineer

Beikang Yizhong Medical Technology

Dec 2021 - Nov 2022 (11 months)

Led backend architecture and core module development for a cloud telemedicine platform, designing HIS integration and Sidekiq workflows to deliver a compliant system used in hospitals.

Ruby on Rails PostgreSQL Redis Sidekiq API Design Telemedicine & Compliance

Senior Ruby on Rails Engineer

Partner Vision InfoTech

Oct 2019 - Jan 2021 (1 year 3 months)

Designed a modular backend for a hyperlocal life platform supporting e-commerce and community features, enabling rapid business iteration and stable continuous experimentation.

Ruby on Rails PostgreSQL Redis React Deployment Sidekiq Docker

Senior Ruby Developer

Beijing Sunshine Procurement InfoTech

Oct 2018 - Oct 2019 (1 year)

Refactored a legacy government procurement and bidding platform into a maintainable Rails architecture and optimized queries and indexing for large-scale datasets used in production procurement workflows.

Ruby on Rails MySQL Redis Sidekiq Elasticsearch Refactoring Database Optimization Stakeholder Management

Senior Ruby on Rails Developer

Beijing Jingyu Network Technology

Nov 2017 - Oct 2018 (11 months)

Led end-to-end delivery of a court case management system, translating legal workflows into technical plans and coordinating cross-functional teams to achieve stable, on-premise deployments.

Ruby on Rails MySQL MongoDB Redis Sidekiq Apache SOLR Requirements Analysis Project Delivery

Senior Ruby on Rails Developer

Guangzhou Lige InfoTech

Sep 2015 - Oct 2017 (2 years 1 month)

Refactored flash-sale and commission systems and introduced Sidekiq async pipelines to enable stable handling of 4,000+ QPS during synchronized flash sales, reducing crashes and infrastructure costs.

Ruby on Rails MySQL Redis Sidekiq Performance Tuning Nginx Scalability

Ruby on Rails Engineer

ShopperPlus.ca

Jan 2013 - Sep 2015 (2 years 8 months)

Built and evolved a full-featured e-commerce platform from ground up, owning architecture, database design, and performance improvements to support growing traffic and feature complexity.