A personal money manager delivered as a PWA. Every income is split into pockets, every expense names the wallet and the pocket it comes out of, and wallet totals always equal pocket totals. I wrote the PRD, designed it, and built it end to end; it runs as a private beta for my partner and our families.
The challenge
Money sits across bank accounts, e-wallets, cash, and foreign currency accounts, and a typical expense tracker only records that money went out. Nobody sees which budget paid for it, so a lifestyle budget runs out unnoticed, and shared costs live in chat threads.
The approach
Two layers on every transaction: a wallet for where the money is, a pocket for what it is for. Each entry is a double-entry journal with a wallet leg and a pocket leg, so balances are computed, never typed. On top sits a phone-first PWA: a keypad sheet that records an expense in three taps, workspaces for couples and families, goals, subscriptions, and split bills.
Key decisions
- Amounts are BigInt minor units on the server, never floating point numbers
- Money moves through one journal function; edits void and revise instead of overwriting
- Multi-tenant workspaces from day one, with roles, invitations, and per-workspace budget periods
- A PWA instead of native apps, so one codebase installs on every phone in the family
- AI is optional: receipt scanning helps, but the app works fully without it