Jimmy Hwang
Product engineer · Berlin

Software that works
in the real world.

For early teams building something new. I design the product, the system behind it and the AI-agent workflows that run it, and I own what goes live.

Book a call Hiring? Email me See portfolio ↓

partyx.info/console

Organiser console I built: money in, refunds to decide, a dispute to answer

PartyX iOS app: your ticket live on the lock screen, doors open

Live paymentsCheckout to refund

One engineerDesign to production

PartyX — designed, built and running in production.Explore the screens

My work runs every day at

Stockholm Arlanda Airport
ArcelorMittal
Eramet
PartyX

Services

What does your product need next?

Teams

Full time

A senior engineer in your team, owning features end to end.

From €600/day

3–12 months · start now

Any stack
Shipping in week one
Berlin or remote

Discuss a contract

Products

Build or rebuild

A new product, rebuild or migration, from design to launch.

By milestone

Fixed price or day rate

Clear milestones
Shipped with AI, tested
Launched and handed over

Discuss a build

Ongoing

Part time

A senior engineer two or three days a week.

From €600/day

Monthly · Berlin or remote

Fixed days each week
Weekly progress
Cancel monthly

Discuss part time

Not sure which? Book a call and we’ll pick the first step together.

Portfolio

Built, shipped, running.

Close to users.

Operators use my WiTTRA console every shift. Their feedback becomes releases.

Owns the whole system.

PartyX payments, payouts, door, deploys and cloud cost: all mine.

Ships in week one.

AI writes much of the code. I own the decisions, tests and release.

PartyX

Designed, built and operated alone: web and iOS apps, checkout, passes, refunds, the door and the organiser console.

7 apps2,264 tests at releaseStripe end to end

Used every shift at Stockholm Arlanda Airport, ArcelorMittal and Eramet.

WiTTRA Networks

Customer-facing operator console, supporting APIs and realtime data. Senior engineer since 2023.

Enterprise customersContinuous releases

Systems and workflows

The system behind the screens.

Design boards from PartyX. Each one is drawn from the real code and data, and a check fails when they drift apart.

PartyX system map: every Worker, workflow, database and bucket, and how they connect — System map
Every service, store and queue in production, drawn from one file the build checks against the code.

Ops design: agents do the work, humans see it and step in — Agents work, people decide
Agents draft and check; every send passes six gates; the first ten of anything new wait for a person.

Ops console: the work graph that orders what the agents build next — Work graph
The board that orders the agents' work: projects, the lines inside them, what blocks what, and which pull request proves each one.

Organiser console: money in, refunds to decide, a dispute to answer — **Organiser console**Money in, refunds to decide

iOS app: the ticket live on the lock screen, doors open — **iOS app**Your ticket on the lock screen

Organiser console: the door, guests checked in and a scan button — **Organiser console**Working the door

iOS door app: scan a pass, let the guest in — **Door app**Scan, let in

Web app: a guest's pass, ready at the door — **Web app**Your pass for tonight

Apple Wallet pass for an event — **Wallet**The pass in Apple Wallet

Organiser console: regulars, filtered and invited in one click — **Organiser console**Regulars, invited in one click

People: organisers, venues and guests in one network — **People**The network around the night

Web app: messages from friends and events — **Web app**Friends and event chats

iOS widgets: next event and tonight in Berlin — **iOS widgets**Next event at a glance

A collective's public page with its events — **Social**A collective's page

Process

How it works.

15-minute call

What’s blocked and what must work. Free.

Written scope

Priorities, price and how we measure success.

Build and hand over

Tested releases. You own the code and accounts.

Hi, I'm Jimmy.

Senior product engineer in Berlin. I built the operator console used every shift at Stockholm Arlanda Airport, and I built and run PartyX alone.

Agents do most of the typing. My work is the system: what the product does, how the pieces connect, the rules the agents follow and the checks before anything ships.

Looking for an early team in Berlin that is building something new. Open to selected projects.

Before we start.

What does it cost?

Projects: fixed price after a short review. Contracts: from €600/day. Always in writing first.

How do we start?

A 15-minute call, then a written scope.

What happens after launch?

You own the code and every account. Support can be added.

Can you work on an AI-built product?

Yes. I review it first, then fix or finish what matters.

Book a call

Book 15 minutes.

Times shown in your timezone.

Prefer email? founder@partyx.infoPrefer a CV? One page, PDF

Software that worksin the real world.