Personal finance app
An invite-only spending tracker. Users keep wallets, set a budget per category and can log a transaction by typing a sentence.
- Year
- 2026, in progress
- Role
- Solo build: web client, API, AI service
- Type
- Own product
- Next.js
- Go
- PostgreSQL
- Python
- FastAPI
- React Native
- TanStack Query
- Zustand
What Tommy built
- 01
Next.js web client. A React Native (Expo) client is in progress.
- 02
Go API on PostgreSQL with sqlc. Every query is scoped to the signed-in user.
- 03
Money is stored as integer cents. A balance change and its transaction are written in one database transaction.
- 04
Invite-only accounts with one session per device. Signing a device out takes effect on its next request.
- 05
A Python service turns a typed sentence into a draft transaction. Nothing is saved until the user confirms it.
The hard part
Getting structured data out of a language model. Describing the JSON shape in the prompt was not reliable, so extraction moved to tool calling with a fixed schema.