Hwi Jin Jang · AI/ML Engineer

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Applied AI/ML engineer. I build agent platforms 11,000+ people use. Also, this pack.

Python ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ PlaywrightPython ✦ TypeScript ✦ Java ✦ Kotlin ✦ React ✦ Next.js ✦ FastAPI ✦ Spring Boot ✦ GraphQL ✦ OpenAI ✦ Agno ✦ RAG ✦ AWS ✦ Azure ✦ Playwright

Portrait of Hwi Jin Jang — Hwi Jin Jang
Irvine, CA
01/05

I'm an AI/ML engineer at Optum, where I lead an 8-engineer team building the central observability platform other teams plug their AI telemetry into. Before that I built multi-tenant agent platforms, multi-agent orchestration and RAG pipelines that more than 11,000 people rely on.

I studied Computer Science at Grinnell College and interned at Amazon before Optum. Most days I'm in Python, TypeScript and Java, with FastAPI, Next.js and React, on AWS and Azure, building agents with OpenAI and Agno.

Python
TypeScript
Java
Kotlin
React
Next.js
FastAPI
Spring Boot
GraphQL
OpenAI
Agno
RAG
AWS
Azure
Playwright

Numbers from systems in production, not demos.

people using platforms I built

production AI products reporting into one telemetry platform

production agents on Sage AI

user stories written by StoryCraft

less time spent drawing architecture

developers shipping TestGenie suites

Experience

Threading it all together

Feb 2026 to now

AI/ML Engineer

Optum · Optum Health AI

Engineering lead for an 8-engineer team: translating product requirements into technical user stories, driving sprint planning and work allocation, and unblocking engineers on architecture and implementation challenges.

AI observability platform

The central home for AI agent and API telemetry, built on Arize and OpenTelemetry. 8+ production products report into it, and other teams onboard their metrics with my team's support.

Querying Arize live0:00

Precomputed + cached12 ms

Metrics pipeline

Server-side ingestion and caching that precomputes Arize telemetry and serves it from the database. Analytics queries went from 2 to 6 minutes to milliseconds.

Program management platform

Built 0 to 1. Moved executive healthcare program management off spreadsheets into a system of record for leadership and clinicians.

Leadership uses the observability platform to track adoption, usage and operational metrics across products and to generate reports.
Architected scalable backend services and database schemas for structured operational data, document storage, workflow management and executive reporting.

Jul 2023 to Feb 2026

Associate Software Engineer

Optum · Sage AI · Optum Clinical Management

Multi-tenant AI platform where 11,000+ people create, configure and deploy LLM agents through scalable APIs.

Sage AIMulti-agent orchestration with dynamic prompt routing. 900+ production agents.
RAG pipelineKnowledge base and retrieval that raised accuracy and cut hallucination.
StoryCraftWorkflow automation. 125,000+ user stories, 52,000+ engineering tickets.
ArchWizardNatural language to architecture diagrams. 61% faster design.
TestGenieGenerates and deploys Playwright suites via GitHub APIs. 400+ devs.

May 2022 to Aug 2022

Software Development Engineer Intern

Amazon · Cross Border Transportation

Saved, shareable filters and real-time status search across 15,000+ international shipments.

ElasticSearch and AWS Lambda behind TypeGraphQL, querying shipment data in S3.
Wrote and presented high-level and low-level design docs to align stakeholders.
Lazy loading for real-time monitoring of 15,000+ shipments.

Things I built for fun

01/04

Youtify

Heard it on YouTube. Saved on Spotify.

Never miss a song you heard on YouTube. Youtify finds it and gets it onto Spotify.

React
Node.js
Ollama

Code

02/04

PlusOne

Events and RSVPs, minus the group chat.

Simplifying event creation and RSVPs.

Next.js
TypeScript
Firebase

Live Code

03/04

Group Alarm

For friends who are always late.

Are your friends always late to hangouts? Group Alarm keeps the whole group on time.

Android
Kotlin
Firebase

Code

04/04Coming soon

Aethos

A marketplace for fitness creators.

A fitness creator marketplace experience.

Next.js
TypeScript
Vercel

Live

One in ten packs hides a Secret Rare.

This one didn't. Its page stays locked until you pull it.

Open to full-time roles and interesting problems. Based in Irvine, CA.

HwiJinJang

HwiHwiJinJinJangJang

About me