PROJECT — GOOGLE DEVELOPER STUDENT CLUBS (GDSC) WASEDA

THE BRIDGE HACKATHON

A one-night, cross-campus hackathon where five GDSC chapters across Korea and Japan built working prototypes for the UN Sustainable Development Goals using Google's products and services. Our team built ClothesBridge — a trust-first way to trade and lend clothes.

FEB 11–12, 2023 · EAST ASIA GDSC GLOBAL COLLAB HACKATHON · ROLE: BACKEND, GDSC WASEDA TEAM

The Brief

The Bridge Hackathon (formally the East Asia GDSC Global Collab Hackathon) brought together Google Developer Student Club chapters from GDSC Waseda, GDSC Senshu, GDSC Keio, GDSC SWU, and KUGODS for one overnight sprint. Each team had to pick at least one UN Sustainable Development Goal and build a working solution around it using at least one Google product or service, then present it the following morning.

Overnight hackathon 5 GDSC chapters Korea × Japan UN SDGs

The Idea — ClothesBridge

Fast fashion is cheap because its environmental cost is hidden — carbon-heavy production, huge water use, and microplastic shedding that ends up landfilled or incinerated within a year or two of purchase. We set out to make it easier to keep clothes circulating instead of discarding them: a customer-to-customer trading and lending app, in the spirit of Korea's Danggeun Market (당근마켓), built specifically for clothes.

A pure peer-to-peer lending model has an obvious hole, though: moral hazard. If a borrower damages or fails to return an item, the lender has no recourse. So ClothesBridge doesn't just connect two users and step away — it inspects each item's condition before the handover and again afterward. If a discrepancy shows up — damage, loss, non-return — the party responsible is fined, and that fine both compensates the other party and funds the service itself.

C2C trading & lending Anti fast-fashion waste Trust & verification layer

How It Works

  1. A user lists an item to trade or lend, with photos and condition notes.
  2. ClothesBridge logs the item's condition before it changes hands.
  3. The item is exchanged directly between users, peer-to-peer.
  4. ClothesBridge checks the item's condition again after the trade or the loan period ends.
  5. If the condition doesn't match — moral hazard — the responsible party is fined; the fine compensates the other party and is how the service earns revenue.

Design Process

From a paper wireframe and information architecture to a working Android build in well under 24 hours — login, home feed, item posting, product detail, and profile.

Hand-drawn wireframes and information architecture diagram for ClothesBridge
Early paper wireframes and the information architecture (IA) map.
Completed screen designs for launch, login, home, my page, posting, and product pages
Completed screens — launch, login, home, posting, and product pages — alongside designs still in progress.
Design system: brand colors, text colors, button colors, and additional product page variants
The shared design system — brand palette, type colors, and button states.
Final screen set covering launch, search, posting, free and rental product pages, and my page
Final screen set: launch, search, posting, free/rental product pages, and profile.

Built With

Android · Kotlin Firebase Authentication Google Sign-In Material Components Figma

Presentation

Presenting the ClothesBridge impact estimates on stage at the hackathon's closing session

Recognition

Certificate of Participation, East Asia GDSC Global Collab Hackathon, February 11–12, 2023 — co-signed by the Korea and Japan head organizers of GDSC SWU, GDSC Senshu, GDSC Waseda, KUGODS, and GDSC Keio.

Certificate of Participation in the Bridge Hackathon, awarded to Kyungmin Park
GitHub Repo ↗ ← Back to Careers