Yuwei Liang
Summary
Software engineer with 10+ years shipping production e-commerce, marketplace, payments, and billing systems at scale — backend services, distributed systems, and full-stack web. Now inside a 1M-line Django OMS/WMS from 2016, where the hard part is not writing the change but proving it is safe — characterization and golden-master suites, and a mutation-testing harness that verifies the tests can actually catch the defect.
Experience
Cart.com — ShopHouzz MarketplaceFeb 2026 – Present
Software Engineer, Billing & AccountingRemote
- Vendor Payouts: Single-handedly designed, built, and shipped the ShopHouzz vendor payout system end-to-end in a matter of weeks, processing millions of dollars in vendor disbursements shortly after launch.
- Vendor Banking: Designed the ShopHouzz vendor banking service (AWS Lambda + DynamoDB + Plaid) for onboarding and ACH flows; live in dev as of Apr 2026.
- Vendor Integration Reliability: Lead responder for the SPS Commerce EDI pipeline processing 1,000+ files daily across 200+ vendors — diagnosing data, mapping, and reliability issues to keep partner integrations running.
- Legacy OMS/WMS Ownership: Sole owner of the inbound-PO ship-complete hold system inside a 1M-line Django OMS/WMS first committed in 2016 — hold evaluator, FIFO release, per-tenant cap, and all ten migration and test files, no other author. The system tracks 300k+ active bin locations across 20 warehouses and 65 tenants.
- Test Verification: Built a mutation-testing harness that perturbs production source, runs the suite, and reports whether the defect was actually caught — written after a test that was green, with correct assertions, still failed to detect the bug it existed for. Restores source on every exit path, including SIGTERM.
- AI Delivery Standards: After an AI-authored fix passed 6 unit, 15 integration and 4 end-to-end tests and still shipped a worse defect to UAT, traced it to the colliding collaborator being mocked in all eight tests, and turned the postmortem into a written red-first rule now enforced across four agent contracts.
Houzz, Inc. — Marketplace2018 – Feb 2026
Full Stack Software EngineerLos Angeles, CA
- Checkout & Payments: Re-architected order-creation workflow, cutting API response time by 90%. Integrated Apple Pay Express Checkout for mobile web, contributing to a 20%+ GMV lift on that checkout surface.
- Billing & Accounting: Built TIN/EIN tax-compliance system integrated with NetSuite, helping 3,000+ partners avoid IRS penalties. Recovered tens of thousands in overpaid sales tax via a comprehensive Avalara API integration.
- Payment Terms: Led multi-term payment system that reduced engineering involvement in net-term setup by 80%; shipped a 2% quick-pay incentive generating meaningful contribution margin.
- Product Ads: Diagnosed and fixed a critical Google Ads conversion-tracking bug, improving ROI measurement accuracy by 35% and unblocking data-driven campaign optimization.
- Supplier BI: Led engineering of supplier-insight reporting platform serving 1,000+ active vendors with sales, inventory, and ads analytics.
Zobrist Consulting Group2015 – 2018
Software DeveloperLos Angeles, CA
- Led development of Mobilecom, a SaaS mobile-first storefront for IBM WebSphere Commerce; client deployments saw mobile conversion-rate improvements of ~25%.
Projects
LoopiiMar 2026 – Present
Festival companion app — Coachella 2026
- Solo-Built & Shipped: Designed, built, and shipped Loopii — a React Native (Expo) iOS app — solo from zero to TestFlight in ~6 weeks, used by a private squad on the ground at Coachella 2026 W2.
- Claude-Driven UX: Drove the entire UX system — screens, navigation, day/night theming with 4 colorways, component composition — with Claude as the design partner, iterating on AI-generated design previews before translating to React Native.
- AI & Release Engineering: Integrated a Claude-powered in-app FAQ assistant and artist-recommendations engine; automated TestFlight delivery with Fastlane (auto-version bump, build, upload, GitHub release) behind a one-command deploy.
Technical Skills
Languages: Java, Python, JavaScript/TypeScript, PHP, SQL
Backend: REST/GraphQL APIs, microservices, distributed systems, event-driven architectures, query optimization, Node.js
Frontend & Mobile: React, Redux, React Native (Expo), HTML5, CSS3, responsive web
Data & Storage: MySQL, Postgres, Snowflake, Redis, DynamoDB, Elasticsearch, Solr, data pipelines
Cloud, DevOps & Observability: AWS (Lambda, DynamoDB, S3, API Gateway), Firebase (Firestore, Cloud Functions, Auth), Kubernetes, Docker, Terraform, CI/CD, Datadog, Grafana, on-call rotation
Integrations: NetSuite, Avalara/AvaTax, Stripe, Plaid, Apple Pay, Google Ads
AI & Developer Tooling: Claude Code, agentic development workflows, agent contracts and capability guards, LLM-assisted code review, MCP servers
Testing & Legacy Change Safety: characterization testing, golden-master suites, mutation testing, Playwright, pytest, Django test framework
Education
M.S., Software Engineering University of California, Irvine
2015B.S., Information Security Beijing University of Posts and Telecommunications
2013