Amortization ScheduleNo sign-inRow-by-row loan amortization schedules: monthly or daily accrual, extra principal, PMI, biweekly.Body MetricsNo sign-inConvert height and weight, compute BMI, TDEE and protein targets with error bounds.Check Digit ValidatorNo sign-inValidates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digitColor CompanionNo sign-inConvert colours between hex, RGB, HSL, OKLCH and CMYK, and compute harmonies.Due DateNo sign-inEstimate a due date from LMP, conception, or ultrasound, with ACOG redating rules.JSON to TypesNo sign-inConvert JSON samples into TypeScript interfaces and Zod schemas, with inference caveats.Penny RoundingNo sign-inRound cash totals to the nearest nickel correctly — after tax, on the total, cash only.Project GumballNo sign-inOne MCP server exposing every tool in the Gumball portfolio.Regex ExplainerNo sign-inExplain a regex in plain English and detect catastrophic backtracking risk.Sports RulesNo sign-inWork an offside call through IFAB Law 11 or NHL Rule 83, step by step.Timezone TruthNo sign-inConvert times between IANA zones and detect skipped or ambiguous DST local times.Words in ContextNo sign-inWords-in-context vocabulary practice questions with distractor explanations.