Johnny Lin

Cross-border commerce & operations platform

• Joined as the first engineer and own technical planning, architecture and production delivery across four connected commerce and operations applications.
• Guide another engineer developing the staff workspace and customer portal, translating requirements into assigned tasks, guiding technical decisions and integrating their work with shared accounts, data access and deployment.
• Implemented transactional balance updates, inventory locking and conditional state transitions for checkout, payment, cancellation and refunds, with daily reconciliation against source transactions.
• Built commission settlement with duplicate-payout guards and refund adjustments based on recorded calculation inputs, preserving traceability across retries and reversals.
• Separated application access with database roles and row-level security; scoped customer queries to the authenticated account and recorded staff access to protected records, verified with PostgreSQL integration tests.
• Delivered electronic document signing with versioned templates, expiring links, document-hash checks, signed PDF generation and hash-linked audit events.

TechnologyTypeScript · Next.js · React · PostgreSQL · Drizzle · Stripe · Vitest · Testcontainers · GitHub Actions

NoirsBoxes · Remote, Taiwan

• Built the video pipeline for a Telegram-operated marketing AI agent, turning product specifications and assets into branded 15–30-second videos in under 20 minutes.
• Integrated ElevenLabs text-to-speech and Whisper captions to produce English, Chinese, Japanese and German versions.
• Automated 16:9 and 9:16 video exports and handoff to a partner-built social publishing agent.

TechnologyPython · FFmpeg · MoviePy · Runway ML · ComfyUI · ElevenLabs · Whisper · Telegram Bot

Defintek Ltd

• Built Web3 proofs of concept covering on-chain fund management and RWA tokenization, with separate fund and stock-lending applications.
• Connected web applications to smart contracts and testnet infrastructure, including wallet flows, Enzyme, ERC-3643, Chainlink and Compound experiments.
• Delivered an RWA stock-lending PoC at a hackathon and received an Honorable Prize.

TechnologyNext.js · TypeScript · Solidity · Ethers.js · Hardhat · Foundry · Enzyme · ERC-3643 · Chainlink · Compound III

Cross-border e-commerce

• Owned the company's payment gateway: checkout front end, provider integrations and the data flow between them.
• Integrated local payment providers so each market could offer familiar payment methods.
• Built a CODA integration that replaced repetitive manual matching with exception-based bank reconciliation.
• Hardened webhook handling with idempotency keys and provider-of-truth payment state.

TechnologyJava · Spring Boot · React · Oracle · Local payment provider APIs · CODA

University of Illinois Urbana-Champaign

• CS425 Distributed Systems · databases · cloud architecture.