Currency Converter
Convert currencies with a visible editable rate, inverse rate, and current, cached, stale, or manual freshness state using ECB-filtered reference data.
Interactive calculatorOpen calculatorFinance & Everyday Money Calculators
Compare currency, bills, discounts, and fixed-rate loan scenarios with visible rates, rounding, and assumptions.
Available calculators
Choose a focused tool, keep the method and units visible, and compare scenarios without sending deterministic inputs to a calculation server.
Tip & Split Bill Calculator
Calculate tip, group total, and per-person amount with explicit subtotal or after-tax basis and optional upward rounding.
Interactive calculatorOpen calculatorShopping Discount Calculator
Apply two sequential percentage discounts, an order coupon, quantity, and entered sales-tax rate to see final price and savings.
Interactive calculatorOpen calculatorMortgage & Loan Calculator
Estimate fixed-rate mortgage principal and interest, entered taxes, insurance, HOA, extra payments, payoff time, and annual amortization.
Interactive calculatorOpen calculatorHow this shelf is organized
Deterministic by default
Arithmetic, dates, units, bills, discounts, and loan schedules run in the browser.
Assumptions stay nearby
Every result retains its operation, unit, rate, or model boundary.
External data is dated
When a tool requests reference data, freshness and cached state appear beside the input.