How Nep built Nếp, an automatic expense tracker for Vietnam, going from first commit to App Store submission in 6 days, and reaching 2,300+ users in its first 10 days.
In Vietnam, most everyday payments go through bank transfers by scanning a VietQR code. People pay dozens of times a week, but their spending is scattered across bank apps, and logging each payment by hand is tedious, so most people give up tracking within days. iOS apps cannot read banking notifications, so automatic tracking has to work differently.
Nếp makes the payment itself the logging step. You scan a VietQR code inside Nếp. The app reads the amount and recipient, opens your banking app with the transfer ready, and records the expense automatically. Everything stays on the iPhone: no account, no server, no bank login. Recurring recipients get remembered names. It is a personal expense log, not a bank or payment service: Nếp never holds or moves money.
Nep has one human: the founder, who decides what to build and who it is for. The building is done by specialised Claude Code agents, each with a written role, file scope and checklist. Opus plans and reviews; Sonnet writes and tests code.
| Role | What the agent does |
|---|---|
| Planner and architect | Turns founder decisions into specs, challenges the architecture, keeps a decision log |
| BA and UX | User flows, Vietnamese copy, Apple Human Interface Guidelines checks |
| Engineer | Writes SwiftUI code strictly within the files listed in each task ticket |
| Tester and visual QC | Builds, runs the app on the iOS Simulator, takes screenshots, files reproducible bugs |
| Reviewer | Independent review of every diff before the founder sees it |
| Release | Release checklist, versioning, App Store submission notes |
| Researcher and marketing | Competitor and user research, content plans for launch |
| Scribe and chronicler | Handoff notes, changelog and a public build diary |
14 agent roles in total. Every task is a ticket; nothing is called "done" until the build passes and the screenshots have been checked. The founder approves every commit and every App Store submission.
| Calendar time, first commit to today | 26 days (24 active days) |
| Commits | 291 |
| Swift code | about 34,500 lines |
| Versions shipped to App Store Connect | 1.0 to 1.0.8 |
| Team | 1 founder + 14 Claude Code agent roles |
Our second app, Living Frame, is a family photo widget for Vietnamese families and is being built the same way. Claude Code remains our whole development team: planning, coding, testing and review for both apps.