Can a prompt replace YNAB?

Build a zero-based budgeting app: accounts and categories, grouped (e.g. 'Bills', 'Fun money'), where every dollar of income has to be assigned to a category before it counts as budgeted — show a running 'to be assigned' total that turns visibly negative if you over-assign. A monthly grid per category: assigned, spent, and available, with unspent balances rolling forward into the next month automatically. Transactions get entered by hand or imported from a bank's CSV export, with payee-to-category memory so repeat payees auto-fill next time. Add a reconcile flow: enter your real bank balance, and the app shows the difference against your recorded transactions so you can find what's missing. Keep simple reports: spending by category per month, net worth over time. Back up the database file on a schedule, since it's the only copy of your financial history.

Do not build automatic bank account syncing — that needs a paid data-aggregation service and handling your actual bank credentials, which is real infrastructure and a real trust liability, not a personal weekend project. A CSV import habit, done weekly, is the honest trade for not paying for that connection.