How you choose to pay your developer is up to you. We recommend using a verified service such as PayPal, Stripe, Square, Venmo or bank wiring service. An alternative secure method would be to employ a third-party escrow service that would hold funds until work is completed, then release the funds when the work has been verified to be complete.
We suggest communicating with your developer how they prefer to be paid, then use that method if it works for you, as well. Be flexible, timely and secure in providing cash payments.