I Build Systems That Scale.
Your Business Grows. Guaranteed.
Senior Full Stack Developer with 8+ years building production systems at enterprise scale. I've shipped payment gateways processing 500K+ daily transactions and SaaS platforms serving Fortune 500 clients. Core stack: Java, Spring Boot, React, and AWS/GCP -- but I deliver across Node.js, TypeScript, Python, and whatever your team runs on.
About Me
Engineering Excellence, Delivered on Time
I'm a senior full stack developer based in Ottawa, Canada. I build production systems that perform under pressure -- at any scale, in any industry. Payment gateways handling half a million daily transactions. Enterprise SaaS platforms serving Fortune 500 clients. High-traffic media services scaling to 100K+ requests per second. Every engagement gets the same engineering rigour, ownership, and accountability.
I architect solutions, not just code. Reliability, security, performance, and long-term maintainability are built in from day one. I back every project with a 100% money-back guarantee because I'm confident in what I deliver.
Enterprise Scale
I build systems for Fortune 500 clients like New York Life, Prudential, and Voya. These systems handle 500K+ daily transactions with zero financial loss.
Performance Under Pressure
99.9% uptime. Sub-150ms P99 latencies. Systems scaling to 100K+ requests per second. I engineer for the load you need tomorrow, not just today.
True Full Stack Ownership
Database schema to pixel-perfect UI. REST APIs to cloud infrastructure. I own the entire stack -- no handoffs, no gaps. One accountable engineer across every layer.
Pragmatic Problem Solver
I adapt to your stack, your constraints, and your goals. Greenfield build, legacy modernization, or critical performance fix -- I pick the right solution for your context, not the trendiest technology.
Services
What I Can Build for You
High-performance full-stack engineering for businesses that cannot afford to fail at scale. Greenfield builds, critical system overhauls, and everything in between -- delivered production-ready.
Full Stack Development
End-to-end application development. Database schema, backend APIs, and polished responsive frontends -- all from one engineer. You get a cohesive product, not a patchwork of handoffs.
Cloud & DevOps
Cloud architecture, migration, and optimization on AWS and GCP. I reduce cost, improve reliability, and scale on demand. Infrastructure as code keeps your environment reproducible, auditable, and free of single points of failure.
System Design & Architecture
I design systems before writing a single line of code. Starting from scratch or scaling an existing product, I define architecture that prevents costly rewrites, handles unexpected growth, and keeps your team moving fast.
Performance Optimization
Slow systems cost you users, revenue, and reputation. I find bottlenecks at every layer -- database queries, API latency, infrastructure limits -- and fix them. Past results: 35% latency reduction, 80% fewer slow queries, 100K+ requests per second.
Security & Compliance
Security is built in from day one, not bolted on at the end. I have led SOC 2 compliance initiatives, implemented MFA/SSO with AWS Cognito, and run vulnerability assessments with industry-standard tools. Your users' data stays safe.
Legacy Modernization
Legacy modernization is high-risk -- I have done it successfully. Monoliths migrated to microservices. Tech stacks upgraded. Database migrations executed with zero downtime and zero data loss. Your business keeps running while I do the work.
Trusted by Fortune 500s
Testimonials
What Clients Say
Hear from colleagues and clients who have worked with me on enterprise-scale systems and high-stakes deliveries.
"If you are looking for a highly technical, hardworking, yet humble fullstack developer, YangYang is the right person for the role. He is the hardest working and humble person I have ever met, his deep knowledge of Java, Spring ecosystem, and database teaches me how scalable enterprise software is built. He is consistently learning including AI, the latest academic papers, and automation, anyone able to work with him is an absolute pleasure."
David Ko
Swift + SwiftUI | Clojure | Java & TypeScript Developer
My Promise to You
100% Money-Back Guarantee
If the delivered work doesn't meet agreed-upon requirements, you get a full refund. No questions asked. That's how confident I am in the results I deliver.
Track Record
Proven Results at Scale
High-traffic media platforms. Fortune 500 enterprise integrations. Every role delivered measurable business impact at scale.
Senior Full Stack Developer
Penguin Benefits
Built and scaled a cloud-native parental leave SaaS platform from zero. Integrated it with Fortune 500 insurance carriers and delivered enterprise-grade security, reliability, and compliance.
- Architected a multi-tenant parental leave SaaS platform (TypeScript, Node.js, React, PostgreSQL, Redis). Integrated with New York Life, Prudential, and Voya -- scaling to 100K+ employees across 100+ employers.
- Built a modular benefit calculation engine in Groovy. Handles earnings thresholds, replacement ratios, and duration rules to produce precise, policy-compliant estimates at scale.
- Migrated auth from Firebase to AWS Cognito with MFA, SSO, and SAML. Cut login-related support tickets by 20% and SSO login errors by 40%.
- Found and resolved performance bottlenecks using JMeter. Cut API latency by 35% and boosted SLA from 99.5% to 99.9%.
- Built a Cypress-based automated regression testing suite. Reduced manual QA effort by 70% and accelerated release cycles from 7 days to 2.
- Led SOC 2 Type II compliance. Hardened AWS infrastructure (IAM, VPC, CloudTrail, WAF, GuardDuty, Config, Inspector) for secure PII processing with Fortune 500 clients.
- Implemented cross-region disaster recovery: RPO under 15 min (automated RDS backups with KMS) and RTO under 2 hrs (full DR stack via CloudFormation).
- Resolved JVM metaspace memory leaks from Groovy classloader issues. Reduced server crash rate by 70%.
- Mentored two mid-level developers. Doubled sprint velocity and strengthened system design expertise across the team.
Tech Stack
Tools & Technologies
Deep roots in Java and cloud-native ecosystems. Proven ability to deliver across the full modern web stack.
Core Stack
Full Toolbox
Hover over any skill to see how I apply it
Get in Touch
Let's Build Something That Scales
Have a system that needs to perform at enterprise scale? Book a free consultation or send me a message -- I'll get back to you within 24 hours.
Ready to Build Systems That Scale?
Let's discuss your project over a free strategy call. I'll review your requirements, propose a scalable architecture, and give you an honest assessment. No strings attached.
Book a Free 30-Min ConsultationNo commitment required. 100% money-back guarantee on all projects.
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No commitment -- just tell me what you're working on.