How to pay for the OpenAI API — adding a card, prepaid credits, and resolving payment failures

The OpenAI API is prepaid. Register your payment details and purchase credits from $5; your balance is then deducted as you use it, and purchased credits expire after one year. If payments with a Korean card keep failing, you can top up through Kunavo from $10 to use the same GPT models with a card, Apple Pay, or Link, and, when checkout is displayed in KRW, with KakaoPay, Naver Pay, PAYCO, Samsung Pay, or Korean cards; the balance does not expire. Kunavo’s GPT pricing is 60~65% cheaper than OpenAI’s list price.

OpenAI API payment methods at a glance

OpenAI 도움말의 Prepaid API billing documentation에 따르면 신규 API 계정은 선불(prepaid) 결제를 씁니다. 청구 개요 화면에서 결제 정보를 추가하고 첫 크레딧을 사는 방식입니다.

• The minimum purchase is $5; the default is $10.
• Purchased credits expire after 1 year and cannot be extended.
• Refunds are not available except where required by law or contract, or in approved exceptions.
• Auto-reload is turned on by default during initial setup, so turn it off if you do not want it.
• The maximum balance an account can hold is determined by its trust tier, based on usage and payment history.

결제 수단을 등록하거나 바꾸면 신용카드에 $5 임시 승인이 걸리고 7일 안에 취소됩니다(Help). 사용료나 크레딧 구매가 아니니 걱정하지 않아도 됩니다.

When domestic card payments are blocked

1. Enable overseas payments. 카드사 앱에서 해외 결제가 차단돼 있으면 승인 자체가 나지 않습니다(KB Kookmin Card overseas usage guide).
2. Block overseas transactions in local currency (DCC). 달러 결제가 원화로 한 번 더 환산되면 수수료가 붙습니다. 카드사에서 DCC를 차단해 두면 달러로 결제됩니다(KB Kookmin Card DCC guide).
3. Check the international brand. Domestic-only cards without an international brand such as Visa or Mastercard cannot be used with overseas merchants.

Alternative: Use GPT with Kunavo

Kunavo는 Claude·GPT를 하나의 키와 하나의 선불 잔액으로 쓰는 OpenAI 호환 API 게이트웨이입니다. 결제는 Stripe Checkout에서 카드(Visa·Mastercard·Amex·JCB·UnionPay), Apple Pay, Google Pay, Link로 하고, 결제 화면이 원화(₩)로 표시되면 카카오페이·네이버페이·PAYCO·삼성페이·국내 카드도 선택지에 나옵니다. 원화 금액에는 Stripe 환전 수수료 2~4%가 들어 있고, 달러로 결제하면 이 수수료는 없지만 국내 간편결제와 국내 카드는 사라집니다(Stripe guide, 2026년 10월 3일 확인). 토스페이는 받지 않습니다. 최소 충전은 $10, 잔액은 만료되지 않으며 실패한 요청은 과금되지 않습니다.

These methods are for topping up your Kunavo balance to use the GPT API; they cannot be used for API credits paid directly to OpenAI or for ChatGPT subscription payments.

Full pricing by model is listed under GPT API pricing, and Claude payment details under Claude KakaoPay payment.

How to pay with Kunavo

1. Sign up with an email address or Google account. You do not need to add a card when signing up.
2. Choose an amount on the payment page. The minimum is $10.
3. Pay in Stripe Checkout with a card, Apple Pay, Google Pay, or Link. If the checkout is displayed in KRW, you can also pay with KakaoPay, Naver Pay, PAYCO, Samsung Pay, or a domestic card.
4. Once the payment is approved, the balance is added. If it does not appear immediately, refresh the payment page and do not pay again beforehand. Create the key under API keys.
5. Send your first request:

# 충전이 끝나면 첫 호출은 이렇습니다.
curl https://api.kunavo.com/v1/chat/completions \
  -H "Authorization: Bearer $KUNAVO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-6-sol",
    "messages": [{"role": "user", "content": "한 줄로: 결제 잘 됐나요?"}]
  }'

Frequently asked questions