We use a Singapore based secure payment processor called SMOOV (their fees are lower than Stripe and Paypal) which accepts Visa and Mastercard.
Note that all payments are processed in SGD, the USD price is a reference price calculated at the official exchange rate of the day.
If you’re in Singapore you also have to option to pay in cash at the UWCSEA Dover Service Office. If you can, we would appreciate it if you take that option, as it allows us to save a little bit on transaction fees, which we can use to cover part of the cost for running this project.