Splid

Splid tracks shared expenses for trips and households, working entirely offline so you don't need internet to split costs. It handles 150+ currencies, making it invaluable for vacations abroad. You can add expenses on the fly and it calculates who owes whom at the end.

It's especially valuable for multi-country trips or houses where roommates earn in different currencies. For ongoing family budgeting with recurring bills, a persistent app like YNAB or Mint is better suited.