International credit cards are honored in Bali and in many shops, hotels and restaurants the cards accepted will be displayed in the window. Popular cards are Visa, Mastercard, Citibank and DinersClub.
Bali has a branch of Citibank located on Jl. Tueku Umar in Denpasar and foreigners living in Bali can sign up for a variety of accounts. Local banks charge 3.25% for using their cards. When you get an account at BCA bank in Bali, they will offer you a BCA Master / Visa and plain BCA card.
Mastercard charges 3% for using its card in Bali. Sometimes shops will charge 3%, (as they get charged 3%), sometimes not. If you lose your credit card while in Bali, the best strategy is contact your bank via phone ASAP. I lost my debit card last year and was able to cancel it and order a new one using online banking.
American Express is not so popular in Bali. The vendor has to wait longer to get paid (as in the US) and has to apply to be a vendor. When shopping in Bali you’ll need to use cash for most things in the street, better shops will be able to handle credit cards.
Here is a list of contact info for the main banks and credit card info in Bali.