Chun-Cheng Lee

Chun-Cheng
Lee.

Backend-focused software engineer. APIs, AI integrations, and payment systems you can click into and verify.

Los Angeles, CA

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Open to backend and full-stack roles

What I build.

Backend & APIs

Django, FastAPI, and Node services with clean REST design, JWT auth, and PostgreSQL behind every endpoint.

Django, FastAPI, PostgreSQL, REST

AI Integration

GPT-4o Vision apps, RAG chatbots with multi-turn memory, and LLM-augmented workflows shipped to production.

GPT-4o, RAG, LangChain, Claude API

Payments & QA

Stripe subscription billing, webhook event processing, and end-to-end test automation that keeps releases safe.

Stripe, Webhooks, CI/CD, Test Automation

 

Public projects

 

Live demos

3

Languages spoken

Skills.

Languages
Python, JavaScript, TypeScript, SQL, Java, Kotlin
Backend & Data
Django, Django REST Framework, FastAPI, Flask, Node.js, Express.js, PostgreSQL, MySQL, MongoDB, Redis, REST API Design, JWT Authentication, Google OAuth
Frontend
React, HTML/CSS, Bootstrap, Chrome Extension APIs (MV3)
AI & LLMs
Claude API (streaming, tool use), OpenAI GPT-4o and Vision, RAG with Chroma, MCP servers, SSE streaming, Prompt engineering, Claude Code, Cursor, GitHub Copilot
Payments
Stripe API, Subscription Billing, Invoice Automation, Webhook Event Processing
Testing & DevOps
Unit Testing, Integration Testing, Test Automation, GitHub Actions (CI/CD), Docker, Linux, Git, Heroku, Jira

Real work.

Pulled live from GitHub.

All repositories

Experience.

View resume

AtSquareOne

Software Developer

Apr 2024 – Present

  • Built a guardrailed AI agent for the member chat on atsquareone.org: four filter layers, 10 tools over live data with default-deny grants per app, and a signed two-step confirm so the model never writes data on its own.
  • Split the agent into a standalone service the main site reaches over an internal API, covered by 86 offline tests and an 18-case golden set run against the real model.
  • Own the Stripe billing backend in Django REST Framework: subscriptions, invoices, donations, and course payments, handled through webhooks across six Stripe event types, with prices resolved at runtime by lookup key.
  • Built the earlier RAG chatbot (OpenAI, Chroma) with multilingual intent classification, an H-1B sponsor database from USCIS data, and a visa deadline tracker with reminders.

Incluvie

Web Developer (volunteer, part-time)

Jun 2026 – Sep 2026

  • Cut the JavaScript bundle 78% (2.8 MB to 610 KB) and image payload 54% after finding webpack was shipping development builds to production.
  • Traced a post-deploy outage to Terser mangling a redis-om class name the library derives its search index from, and fixed it by leaving the server bundle unminified.
  • Fixed /articles taking about 20 seconds: the Redis search index was being evicted from a 30 MB instance, so article bodies moved to their own evictable keys. Server rendering falls back to MySQL when Redis is down.
  • Built actor and director pages end to end on the TMDB API, with server-side rendering and Redis caching.

Cal Poly Pomona

Graduate Research Assistant

Feb 2023 – Dec 2023

  • Developed an autonomous driving system on the Quanser QCar platform, with CNN-based real-time object detection across multiple camera feeds.
  • Tuned PID controllers and real-time parameters, cutting measured control latency from 500 ms to 100 ms in lab benchmarks.
  • Built path planning that combines obstacle avoidance, target tracking, and route optimization. Co-authored two academic papers.

ViewSonic

Software QA Engineer

Aug 2021 – Dec 2021

  • Designed and ran automated and manual test cases for ViewBoard display software on Windows, Android, ChromeOS, macOS, and iOS, escalating defects through Jira.
  • Wrote QA workflow documentation and test plan templates the team adopted as standard references, working inside cross-functional Scrum teams.

Synaptics

Firmware QA Assistant Engineer

Mar 2021 – Apr 2021

  • Ran cross-platform test scenarios for touchpad firmware on HP, Dell, and Lenovo hardware, documenting failure modes for the firmware team.

Chunghwa International Communication Network

Summer Intern, programming and marketing

Jul 2017 – Sep 2017

  • Worked on e-payment integrations (SMS, PayPal, convenience-store, QR code, and phone-bill payments) and kept the payment system running.

Contact.