---
title: "Selected Work — Charlie Tang Hoong"
url: https://tanghoong.com/work/
locale: en
description: "Five deliveries from discovery to production: enterprise ERP integration, an OCR and LLM document pipeline, AI request architecture, costed AI feasibility work, and AdTech at scale."
---
# Selected Work

Five deliveries, each written the same way: what the customer was actually trying to do, what was unclear, what I decided, what I built with my own hands, and how it reached production.

## Case 1 — Building against a system we did not own

A multi-role booking and ordering platform went live against an enterprise client's legacy ERP, with the API contract negotiated directly with the client's own engineers and every scope change signed off before it reached engineering.

Read the full case: https://tanghoong.com/work/legacy-erp-booking-platform/

## Case 2 — Taking the typing out of a document workflow that could not go offline

A hybrid OCR and LLM pipeline substantially reduced the manual data entry in a high-volume shipping-document workflow, inside an operation whose source systems had no API and could not be replaced.

Read the full case: https://tanghoong.com/work/ocr-llm-document-pipeline/

## Case 3 — Serving an AI assistant's traffic without holding a connection open

Re-architected an AI customer-support assistant's request path so that a conversation is queued and polled rather than held open on a synchronous connection — delivered and merged.

Read the full case: https://tanghoong.com/work/ai-assistant-queue-architecture/

## Case 4 — Three AI proposals, and the two I advised against

Three AI feasibility engagements in three unrelated domains, each turned into a solution design with a costed build estimate: two were correctly declined on capital cost, and the third was built.

Read the full case: https://tanghoong.com/work/ai-feasibility-assessments/

## Case 5 — The engineering floor: billions of impressions, and a marketplace that ran itself

Eleven years across two stints at the same AdTech company: four as the sole front-end engineer on a platform conversion, then a self-serve advertising marketplace built end to end, then backend services carrying tens of thousands of requests a second.

Read the full case: https://tanghoong.com/work/adtech-scale-marketplace/