Plan a trip together, split the costs, settle up.
Log what you spend in whatever currency you spent it. At the end, one number: who owes whom.
Any currency, honestly
Enter ¥14,800 as ¥14,800. You set the rate your card actually gave you — spread included — and it's frozen the moment you save. Editing it later never rewrites what's already settled.
Splits that add up
¥1,000 three ways is 334 / 333 / 333. Every share is stored, so the parts always sum to the total and nobody quietly loses a yen.
The fewest transfers
Four people, eleven expenses, three currencies — and at the end, two payments. Not everyone paying everyone.
Built for the bit that actually goes wrong
Most of a shared trip is easy. The hard part is three weeks later, when someone paid for the hotel in yen, someone else covered dinners on a card with a worse rate, and one person bought souvenirs that were never shared. That is the part this does properly.