Presentation montage created from the RestMoney interface.
Starting point
Knowing what remains throughout the year
As a self-employed professional, I wanted to know, with each payment, what I could actually treat as available. Revenue alone does not answer that: RestMoney shows the amounts to set aside for contributions and taxes, then estimates what remains. It is a practical way to follow my year, not accounting advice.
Design challenges
Updating the contribution rate without changing calculations for income that has already been recorded.
Showing how an income entry affects the annual estimate, including when it is edited or moved to another year.
Letting people use and reset the demo without affecting my personal data.
Architecture choices
Technical choices suited to a personal tool
01
A rate stored with each income entry
The contribution rate is stored with each payment. Calculations reuse that value instead of the current setting, so a rate change does not alter amounts that have already been tracked.
02
Shared, tested calculation logic
Calculations are grouped into functions used by the dashboard and forms. An income entry’s impact is estimated from the total for its year; tests cover crossing a threshold and changing the year when editing an entry.
03
An isolated, resettable demo
The demo uses a SQLite file separate from my personal data. Resetting it replaces its sample income and settings in one transaction, restoring a consistent state.
In pictures
The dashboard brings together collected revenue, the amounts to set aside and what remains.Income can be searched, sorted and inspected to understand its effect on what remains.
Technologies
A full-stack foundation designed to stay simple
React
TypeScript
TanStack
Tailwind CSS
SQLite
TanStack Start · Better Auth · Drizzle ORM · Bun · Zod · Recharts · Vite
Try the application
Explore RestMoney
The application is available as a demo with fictional data. Displayed amounts are estimates and do not replace tax or accounting advice.
