For remote workers booking a desk in Da Nang, Hanoi or Ho Chi Minh City who want to know how the money actually leaves their pocket each month.

For groups of tourists and mixed local-and-foreign tables who want to pay their own share in a Vietnamese restaurant without one person fronting the whole bill in cash.

For coffee drinkers who start in the Hanoi Old Quarter and end up somewhere with one ATM and no card machine — which payment method to rely on, and where each one breaks.