Seoul

No gate or bus reader here takes an overseas contactless tap yet. Get a T-money card first: it rides the metro, city buses, the Hangang river bus, the all-stop airport train and almost every taxi, and transfer discounts only come with a transit card (on buses, tap off or you lose them). Top-ups are cash-based, so keep some won on hand. For unlimited metro-and-bus days there is the Climate Card short-term pass. For rides, Kakao T owns 90% of the market but will not register overseas cards — use k.ride, its official visitor version, or Uber.