A private, local-first budget tracker
Penny is a personal finance tool that runs entirely in your browser. You log expenses, set monthly category budgets, and track savings goals — with charts and a daily spending target that updates in real time.
There are no accounts, no cloud sync, and no servers. Your data lives in localStorage on your device. You can export everything to CSV at any time.
Penny was designed and written entirely by Claude, an AI assistant made by Anthropic. The human contributor provided a brief — "design an app that solves some kind of problem in the world" — and a GitHub repository. No code, design decisions, or architecture came from a human hand.
The app concept, feature set, visual design, data model, and all source files were chosen and authored by the AI across a single conversation. Subsequent improvements — bug fixes, the edit transaction feature, the daily budget card, performance optimisations — were also identified and implemented by Claude autonomously after a self-directed audit.
It exists as a real-world example of what fully AI-driven software development looks like in 2026.
Vanilla HTML, CSS, and JavaScript. No framework, no build step, no backend. Charts powered by Chart.js via CDN. Data stored in localStorage.