jarvisbox

jarvisbox /

Finance tools

20 browser-based personal finance calculators — compound interest, mortgage, amortization, debt snowball, emergency fund, Rule of 72, house affordability, 401(k), inflation, tip splitting, VAT, payroll, and more. No signup, no cloud, nothing leaves your device.

100% client-side · no uploads · no telemetry

Finance Tools

Why browser-only finance tools?

Salary figures, investment amounts, and business margins are sensitive data. Sending them to a third-party server — even a reputable one — creates an unnecessary privacy risk. Every tool on this page runs entirely in your browser: your numbers stay on your device, calculations happen instantly, and the tools work offline once the page has loaded.

Choosing the right tool

For dining: use the Tip Calculator for quick single-person bills or the Bill Splitter for group meals. For travel: the Currency Converter handles 30+ currencies. For personal goals: the Savings Goal Planner, Emergency Fund Calculator, and Retirement Planner show you how far your monthly contributions go. For investing: Compound Interest Calculator, Rule of 72, 401(k) Projection, and Inflation Impact. For real estate: the Mortgage Calculator, Amortization Schedule, and House Affordability Calculator. For business: use the VAT Calculator, Payroll Calculator, Freelance Quote Calculator, Profit Margin Calculator, and Car Lease vs Buy.

常見問題

Do these finance tools send my numbers anywhere?
No. Every tool on this page runs entirely in your browser using JavaScript. Your salary figures, savings amounts, and business data never leave your device — not even temporarily.
Are the currency rates up to date?
The Currency Converter uses reference rates that are periodically updated in the tool. Because the site is static and runs offline-capable, live rates require an API — the static rates are suitable for quick estimates and travel planning.
Which tool should I use for a restaurant bill?
Use the Tip Calculator to work out the gratuity and per-person share in one step. For groups with unequal shares, switch to the Bill Splitter which lets you assign different amounts to each person.
回報這個工具的問題