Peifeng Wang
Full-stack engineer and team lead with 10+ years building products from zero to one — across SaaS, e-commerce, robotics, and supply chain. Led a 10-person engineering team at Geetest while shipping production features. Co-engineered autonomous forklift navigation with CMU researchers at BITO Robotics. Architected a warehouse design automation tool at Shucheng AI, collaborating with co-founders from Stanford and University of Michigan. For the past three years, based in Tokyo and working across Japanese startups building SaaS and e-commerce platforms.
Strong in Python, Go, TypeScript, and Elixir. Comfortable owning the full stack — architecture decisions, backend systems, frontend delivery, and DevOps — in small teams where all of it sits at the same table.
On the side, building sky-finance: a local-first RAG pipeline with sentiment-bucketed retrieval, multi-provider LLM routing, and LLM-as-judge evaluation — running at under $0.50/month.
Shopify-focused e-commerce company. Joined as an early core developer on a new internal SaaS initiative: a timecard management platform developed from its early foundation and currently running in internal pilot. Worked across product requirements, system architecture, real-time workflows, and end-to-end feature delivery.
- •Took ownership of feature design and technical architecture for the timecard SaaS, translating operational requirements into production-ready full-stack implementations.
- •Built a real-time kiosk view with Phoenix LiveView and WebSockets, enabling instant punch-in/out status updates across locations without polling.
- •Developed a live 2D canvas map using sprite graphics and Anime.js to visualize employee state transitions as game-style character movement triggered by punch events.
- •Collaborated closely with the team lead on foundational system design while independently delivering core product functionality from concept to pilot.
Japanese startup building portfolio and commerce products for creators. Stepped into the Lead Engineer role to rebuild the engineering function and deliver the company's commerce platform end-to-end.
- •Took ownership of architecture, delivery priorities, and team operations as Lead Engineer, rebuilding the engineering team and processes from the ground up.
- •Architected and launched a full commerce platform (Rails / Next.js / TypeScript / Stripe) handling 1,000+ transactions with per-order values ranging ¥10K–¥200K, integrated end-to-end from the Foriio main site through to payment settlement.
- •Maintained and refactored Ruby on Rails APIs supporting 2–3 million daily requests, improving stability and resolving recurring performance bottlenecks.
- •Modernized CI/CD pipelines across 10+ projects and 40+ servers — introduced modular GitHub Actions architecture for new projects, replacing monolithic single-file configs on key pipelines to reduce maintenance overhead.
- •Led a team of 4 engineers — conducting interviews, onboarding, task allocation, and priority definition while personally handling the most complex technical deliverables.
Tokyo-based staffing and technology firm serving major Japanese enterprises. First role after relocating to Japan — contributed across client-facing Salesforce projects and internal web development.
- •Delivered Salesforce Marketing Cloud low-code implementations for major Japanese clients including AU and UNITED ARROWS, involving SQL, JavaScript, and data analysis workflows.
- •Rebuilt and launched the company homepage using Flask, replacing the existing site with a cleaner, maintainable codebase.
- •Developed a gaming equipment e-commerce platform using Django, delivering a complete codebase for internal handoff.
Supply chain digitization company incubated by SF Express, China's largest logistics enterprise. Joined as a core engineer and took on Technical Director responsibilities — owning technology selection, architecture, and end-to-end team recruitment alongside a founding team from Stanford and the University of Michigan.
- •Re-architected the company's primary Python-based platform from the ground up after joining — redesigning core systems and establishing new technical foundations across front-end and back-end.
- •Architected and shipped a warehouse design automation tool that generates CAD, 2D, and 3D layout models from parametric web inputs, eliminating manual design cycles for logistics PoC clients.
- •Contributed to a Starbucks demand forecasting project (4,000 stores across China) — responsible for data cleaning pipelines and auxiliary web UI for model input and output.
- •Developed a WeChat Mini Program e-commerce platform for multi-channel sales distribution using Django and Vue.js.
- •Led full-cycle recruitment and managed a team of 5 engineers, owning hiring decisions, onboarding, and technical direction.
Robotics company specializing in autonomous forklifts and AGV systems, with a core team primarily from Carnegie Mellon University. Rebuilt the front-end and back-end of two core systems from scratch — a central control platform and a per-AGV on-board system — integrating directly with ROS in a live warehouse environment.
- •Rebuilt the AGV central control system (Flask / Redis / Vue.js) from scratch — implemented a custom WebSocket bridge to ROS topics for real-time bidirectional communication between the web platform and autonomous forklift fleet.
- •Developed a road network design tool using D3.js that constructs warehouse maps from QR code scans, allowing operators to define nodes, roads, and AGV task routes entirely through a web interface.
- •Built a per-AGV on-board monitoring system with direct ROS integration, enabling real-time status tracking and task management for a fleet of 5–10 autonomous forklifts.
- •Led a development team of 3 engineers across both systems.
Cybersecurity startup best known for CAPTCHA and bot-detection — joined as the 13th employee, grew to ~200 employees and nearly 100 engineers during tenure. First engineering role after a career switch from sales — entered the industry as a self-taught developer and progressed to Web Team Lead within one year.
- •Joined as the sole web developer and became Web Team Lead within one year as the company scaled — ultimately leading a team of 10 engineers across front-end and full-stack projects.
- •Architected and delivered the core B2B customer platform — a user management and API key portal that scaled from under 10K to 200K registered users, rebuilt multiple times (Django → Flask + Django + Vue.js) to keep pace with growth.
- •Developed 10+ production web systems across the full product lifecycle — including three full UI rebuilds of the company homepage, an internal business intelligence dashboard for commercial operations, and web tooling for the machine learning team.
- •Rebuilt the company's primary web infrastructure from Django monolith to a modular Flask + Vue.js architecture, establishing the technical foundation the web team operated on through the company's growth phase.
- •Built an end-to-end financial intelligence platform in Python — market/news ingestion, LLM-assisted cleaning, embedding, RAG retrieval, and strategy analysis, running at under $0.50/month in cloud API costs.
- •Implemented hybrid RAG retrieval with PostgreSQL + pgvector, combining BM25 full-text search and HNSW vector search via Reciprocal Rank Fusion, with sentiment-bucketed context to ensure minority signals reach the model.
- •Designed multi-provider LLM routing across Ollama, OpenAI, and Anthropic Claude — structured outputs, prompt caching (~90% cost reduction), and per-call token/cost tracking surfaced in the dashboard.
- •Built an LLM-as-a-judge evaluation pipeline comparing sentiment-bucketed vs. flat retrieval across faithfulness, coverage, and actionability dimensions.
WO2021184193A1 - Computer-Aided Warehouse Space Planning