Finance
Five calculators that show their working. Each one explains what it models, what it deliberately leaves out, and why the number it gives you might differ from what your bank or your account actually does.
None of them ask who you are. Amounts you type stay in your browser.
- Compound Interest CalculatorModel savings growth with regular deposits and see contributions vs interest year by year.
- Loan CalculatorMonthly payment, total interest, and what an extra payment each month would save you.
- Currency ConverterConvert between 150+ currencies with daily reference rates and a quick-reference table.
- Budget PlannerTrack income against expenses and check your split against the 50/30/20 rule.
- Tip CalculatorTip, total and per-person split — with uneven shares and country tipping norms.
Why these run in your browser
Every page in this section is a static HTML file plus a small JavaScript file. There is no backend, no database and no upload endpoint. When you open an image, a PDF or a spreadsheet here, the file is read by your browser's own File API and stays in the memory of that tab until you close it.
That is a deliberate architectural choice with real consequences. It means we could not look at your files even if we wanted to, it means there are no queues or daily limits, and it means the tools keep working on a plane or a train with no signal. The trade-off is that anything genuinely requiring a server — live exchange rates, for instance — is the exception rather than the rule, and we say so on the page where it applies.