Curve: the card that saved my wallet

Curve is deceptively simple. You link every bank and credit card you own, then use the Curve card at the till. In the app you pick which underlying card the transaction draws from — and, uniquely, you can change your mind up to 30 days later ('Go Back In Time'). Why it matters: 1) You only ever carry one card. 2) You can wait until your statement to decide which card should have taken the hit — great for hitting credit card spend targets. 3) Free tier includes fee-free FX up to a monthly limit. 4) Curve occasionally runs card-linked cashback with partner brands. One caveat: don't use Curve to fund a purchase from a credit card you're carrying a balance on — you'll pay interest. Otherwise, it's the single most useful piece of plastic in my wallet.