Three ways to keep a tab.
The pool is the default.
Default
Pool
Everyone pre-funds.
When the tab opens, each member puts in an agreed amount. Expenses come out of the pot. At close, the remainder goes back to each member pro-rata.
Austin trip, 4 friends, $200 each = $800 pool. Back home, $462 left over = $115.70 a head.
Classic
Track and settle.
Classic Splitwise mode. Everyone pays their own when it's their turn; the app keeps the balance; at the end you settle with the minimum number of transfers.
Brooklyn apartment, 3 roommates. Recurring costs (power, water, internet). Settle up on the 1st of every month.
Rotating
Who's paying this round?
The app rotates who pays each round, in order or at random. Nobody keeps score in their head, nobody complains they've paid more times.
Monthly dinner, 6 friends. Tonight it's Mia. Next month, Noah. Visible rotation, no tracking.