Lester Cheong

Freelance Software Engineer

Self-employed · Jan 2025 – Present

3 paying clients. Delivered a Telegram-based order management system (24-26 daily users, PostgreSQL, role-based access, CRON reports) with real-time SSE push notifications to sales dashboard and message queue throttling with coalescing to respect Telegram rate limits and acknowledge user messages during busy periods

Built a full event activation platform for a local marketing company (SvelteKit, Fastify, PostgreSQL, Redis, Replicate AI, Twilio) — consulted, delivered, maintained, and decommissioned. 9 interactive stations including Snake, claw machine, spot-the-difference, AI avatar passport kiosk, SMS authentication, QR check-in, and admin dashboard. Deployed live with on-site support throughout event duration. Optimized AI generation pipeline during the event via parallel model execution and streaming downloads — reduced generation time by ~67%.

Delivered static display sites (company landing page + restaurant PWA) alongside larger projects

Sole operator on all systems: CI/CD, monitoring, on-call, infrastructure

All production backends deployed on Railway (Fastify, PostgreSQL, zero-downtime deploys)

API Developer, Digital Channels & OpenBanking

OCBC Bank · Mar 2022 – Sep 2024

Started as IGNITE apprentice — built a Node.js CLI that parses Postman collections, auto-generates assertion tests, and displays results on a dashboard, adopted by QA team. Won Rookie of the Year.

Investigated and resolved integration issues for partners onboarded on Connect2OCBC API store

Managed change/management tickets, improving team productivity

Assisted with digital certificate renewals for UAT server, documented renewal practices and implemented database housekeeping in UAT environment

Created Swagger documentation and added APIs to sandbox portal via Wso2 carbon

Taught JavaScript to secondary school students via Code@OCBC

IoT Lock Technician

SG Bike · Nov 2019 – Oct 2021

Performed physical smart bike lock repairs and firmware upgrades, wrote troubleshooting documentation

Reverse-engineered competitor's smart lock debugging software via dnspy decompilation — bypassed access restrictions, handed over as a cost-effective internal tool

Sales Consolidator: Order Pipeline

2026 – Present · Deployed at live events

Replaced manual spreadsheet workflow with a structured order pipeline. Salespersons submit orders via Telegram. PostgreSQL as source of truth. Role-based admin flows, CRON-triggered daily summaries, custom ESLint rules enforcing bot command consistency. Zero data loss since launch. Extended with an AI product catalog intake: upload transcripts and DeepSeek AI structures them into product rows for CSV export.

• TypeScript
• grammY
• Fastify
• PostgreSQL
• LangChain
• DeepSeek
• Railway

Valentino Houseparty: AI Avatar & Interactive Arcade

2025 – Present · Deployed at live events

4-station beauty brand event activation with a retro 90s theme. AI pixel art avatar via Replicate (flux-kontext-pro), Snake game, video stations, QR-code-based navigation, prize claim system. Built as a SvelteKit 5 SPA with Fastify 5 API, Prisma + PostgreSQL, and Redis session cache. Retro Windows 98 UI with 98.css and pink palette. Deployed on Railway. Closest I've been to actual production users — client was happy, event ran live.

• SvelteKit
• Svelte 5
• TypeScript
• Fastify
• Bun
• Prisma
• PostgreSQL
• Redis
• Replicate AI
• QR Code
• Railway

Themelios: AI Accounts Receivables Platform

Jul 2024 – Jan 2025 · Attempted startup (scrapped)

AI-powered platform for business owners to manage invoices, collections, and payment reconciliation. Built with Temporal.io for durable workflow orchestration, Mastra AI agents for email-based receivables conversations, Xero accounting API integration, Stripe payment processing, oRPC type-safe API contracts, and Azure AD authentication. Monorepo with React 19 + Redux Saga frontend, Fastify + Prisma + PostgreSQL backend, and dedicated Temporal worker service. Over-engineered for the problem and never shipped. A lesson in scoping.

• Fastify
• Prisma
• PostgreSQL
• React 19
• Temporal.io
• Mastra AI
• Xero
• Stripe
• oRPC
• Azure AD
• Railway

Ngee Ann Polytechnic

Higher National Diploma, Information Technology · Apr 2020 – Apr 2023

Institute of Technical Education

Nitec, Web Applications · Jan 2018 – Dec 2019

Infrastructure & Homelab

Homelab with multiple machines. Docker, Portainer, Linux systems administration. Railway deployment management. Publishes deployable service templates for Railway (webtop jump server). Router and network device management. Self-hosted VPN server. Cloudflare DNS configuration.

Events

SuperAI Next 2025: full-stack TypeScript submission, 24-hour build. AngelHack 2024: placed 29th of 200 teams (top 15%).