Split Thing is for the money a group shares: a trip away, a flat's bills, a night out. Whoever pays adds the expense, says who it was for, and Split Thing works out what everyone owes. Expenses can be split equally or in any amounts, paid by more than one person, and recorded in any currency.
It is a record of who owes what, not a way to pay. When someone settles up by bank transfer or cash, they record the repayment and the balances follow.
Split Thing runs in the browser at splitthing.com, with sign-in by passkey or password.
What it gives you
Everyone counts
Add people to a group by name. They don't need an account to be part of the sums, and can join later with an invite link.
Any currency
Record an expense in whatever currency it was paid in. Split Thing converts it at the European Central Bank's reference rate, or one you enter.
Settle up simply
Balances are worked out as you go, and simplified so the group settles up in as few payments as possible.