Building a live marketplace in five weeks with AI
Students throw away things other students need. With one co-founder and Claude Code, I built BetterBarter, a give-away and resale board for verified students.
5 weeksfrom idea to a live app
108commits with one co-founder
12 / 12tables protected by row-level security
The situation
The problem
Free and resale groups already exist, but anyone can join them. A campus marketplace only works if everyone is a verified student.
What I did
What I did
- 01
Build with AI, decide as humans
Claude Code wrote code with us in React, TypeScript and Supabase. Every product and security decision needed our approval.
- 02
Check students in the database
School-email checks happen in the database, with a separate board for each university.
- 03
Fix security before launch
We fixed every issue from a security review: row-level security on all 12 tables, rate limits and moderation.
Result
What happened
BetterBarter is live, open source and being tried at Columbia, built for Columbia Climate School's See The Future competition.
Try it: Source
What I learned
- AI makes building faster, but people still decide what's safe to ship.
- Put trust rules in the database, not just the screen.