Four free, no-sign-up calculators for people in the UK: Stamp Duty (SDLT 2026, first-time buyers, second homes), Mortgage repayments & overpayments, Statutory Redundancy Pay, and Holiday Entitlement (incl. the 12.07% rule). Every rule comes from gov.uk and is unit-tested against official examples. Built with plain JavaScript, fast on mobile, open source.
