Quick Tools

Quick Tools is an indie library of free calculators with one rule: one job per page, no signup, everything computed in your browser. The date calculator adds or subtracts days, weeks, or months, or counts whole days between two dates. Business-day mode skips weekends (public holidays stay in the count, and the page says so). It ignores time zones so the day count doesn't drift. Other tools: salary increase, credit card payoff, personal loan, CD interest, work hours with breaks and overtime. Everyday math: ratio, percentage, discount, tip. Developers get a JS regex tester, IPv4 subnet calculator, and JSON formatter. Makers get a UPC check-digit generator and barcode generator. Pages are light, show their formulas, and work fine on a phone.