American System
settling money between friends
The problem
Friends who split bills lose track of who owes what, and asking for money back is awkward.
Outcome
Live, with a one-click test user
Stack
- Next.js
- Chakra UI
- TypeScript
- Cloudflare Workers
- D1
- JWT
What I built
American System is a social network for going Dutch, and Wasuli Bhai is its app. Every pair of friends shares a tab. You send a receipt for someone’s share with a due date, they accept it, mark it paid, and you confirm. Your reputation follows how you pay, in tiers everyone can see: Nawab Sahib, Malik Riaz Jr, Kar len ge bro, Mufta, Karzai and Naya Murga.
How it works
- One Cloudflare Worker serves the Next.js app as static files and the API under
/api, on a D1 (SQLite) database with foreign keys and cascades. - A receipt lifecycle (sent, accepted, rejected, cancelled, paid, confirmed, pardoned) enforced on the server: only the right person can make each move.
- Credit scores from payment history: on time counts in full, late counts half, overdue counts nothing.
- Test users get four demo friends with their own habits, who accept your receipts and confirm your payments instantly. Hina always pays on time; Bilal turns down anything over Rs 5,000.
- Security on Web Crypto alone: PBKDF2 password hashing, HS256 JWTs, rate-limited test users and a daily cleanup cron.
A 28-check smoke test walks the whole API, from the test user’s score moving from 50 to 83 to two real accounts settling a receipt, and checks that nobody can act on or read what isn’t theirs.
