468 free online calculators covering tax, finance, health, unit conversion, math, date, everyday life, and programming. No ads, no sign-up, no popups. Every calculation runs client-side — your data never leaves your browser. Built with Next.js SSG for sub-second load times. Japanese and English bilingual support. New calculators added weekly based on user requests. From BMI and loan payments to hex converters and regex testers — if you need to calculate it, it's probably here.