ChamTax is a free calculator showing how much of a Powerball or Mega Millions jackpot you'd actually take home after taxes — compared across 21 countries of residency (US nonresident withholding + your home country's rules, lump sum or annuity).
It's a static site, zero backend, built on GitHub Pages — no server cost. The tax-rate dataset is open (CC0) on GitHub/Kaggle.
Would love feedback, especially on any country's tax treatment I got wrong.
