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Testing

Learn how to test online payments using a sandbox merchant account and test cards with different 3D Secure flows.

Testing your online payments integration is crucial before going live. SumUp provides sandbox merchant accounts and a comprehensive set of test cards to simulate various payment scenarios, including different 3D Secure authentication flows.

Setting up a Sandbox Merchant Account

Section titled “Setting up a Sandbox Merchant Account”

Before you can test online payments, you need to create a sandbox merchant account in the SumUp Dashboard.

  1. Log in to your SumUp account.

  2. Open the drop-down menu between Support and your user panel.

  3. Select Sandbox merchant account.

How to Use Test Cards

Section titled “How to Use Test Cards”

When testing with card payments, you can use the following common details for all test cards:

  • CVV: Any 3 digits (e.g., 123)
  • Expiry Date: Any future date (e.g., 12/25)
  • Cardholder Name: Any name

Test Successful Payments

Section titled “Test Successful Payments”

Use this section as your primary end-to-end test path. It validates that a payment can be completed successfully without additional customer authentication steps.

What to verify:

  1. Your checkout completes successfully without additional cardholder action
  2. You correctly handle frictionless authentication and continue order processing
  3. Your success path is robust across different card brands
BrandCard NumberExpected Behavior
VISA4200 0000 0000 0091Payment succeeds with frictionless authentication.
VISA4200 0000 0000 0109Authentication is attempted and payment proceeds without challenge.
VISA4200 0000 0000 0026Payment succeeds with frictionless authentication.
VISA4200 0000 0000 0059Authentication is attempted and payment proceeds without challenge.
Mastercard5200 0000 0000 0007Payment succeeds with frictionless authentication.
Mastercard5200 0000 0000 0023Authentication is attempted and payment proceeds without challenge.
Mastercard5200 0000 0000 0056Payment succeeds with frictionless authentication.
Mastercard5200 0000 0000 0106Authentication is attempted and payment proceeds without challenge.
MAESTRO6761 3010 0099 3772Payment succeeds with frictionless authentication.
MAESTRO6706 9811 1111 1113Authentication is attempted and payment proceeds without challenge.
MAESTRO6799 8510 0000 0032Payment succeeds with frictionless authentication.
MAESTRO6007 9301 2345 6780Authentication is attempted and payment proceeds without challenge.
American Express374 5002 6200 1008Payment succeeds with frictionless authentication.
American Express377 2770 8138 2243Authentication is attempted and payment proceeds without challenge.
American Express375 9870 0000 0062Payment succeeds with frictionless authentication.
American Express373 9531 9235 1004Authentication is attempted and payment proceeds without challenge.
Diners / Discover36 1775 8067 7072Payment succeeds with frictionless authentication.
Diners / Discover6011 0004 0000 1008Authentication is attempted and payment proceeds without challenge.
Diners / Discover6011 0100 0000 0003Payment succeeds with frictionless authentication.
Diners / Discover6011 0009 9009 9818Authentication is attempted and payment proceeds without challenge.
JCB3530 1113 3330 0000Payment succeeds with frictionless authentication.
JCB3566 0020 2036 0505Authentication is attempted and payment proceeds without challenge.
JCB3569 9900 1227 8361Payment succeeds with frictionless authentication.
JCB3569 9900 1227 8353Authentication is attempted and payment proceeds without challenge.
Dankort5019 9954 2085 3334Payment succeeds with frictionless authentication.
Dankort5019 9995 3113 7108Authentication is attempted and payment proceeds without challenge.
Dankort5019 9916 5867 2173Payment succeeds with frictionless authentication.
Dankort5019 9915 0365 5373Authentication is attempted and payment proceeds without challenge.
UnionPay6250 9470 0000 0014Payment succeeds with frictionless authentication.
UnionPay6250 9470 0000 0022Authentication is attempted and payment proceeds without challenge.
UnionPay6250 9470 0000 0089Payment succeeds with frictionless authentication.
UnionPay6250 9442 2091 4108Authentication is attempted and payment proceeds without challenge.
Bancontact Link6703 9972 1273 7146Payment succeeds with frictionless authentication.
Bancontact Link6703 9933 5156 0670Authentication is attempted and payment proceeds without challenge.
Bancontact Link6703 9949 4294 1098Payment succeeds with frictionless authentication.
Bancontact Link6703 9916 9450 4181Authentication is attempted and payment proceeds without challenge.

Test Unsuccessful Payments

Section titled “Test Unsuccessful Payments”

Use this section to verify how your integration handles declined or failed payments.

To simulate an unsuccessful payment, create a checkout for amount 42.01, 42.76, or 42.91 (depending on currency, for example 4201 in minor units1). These amounts result in a failed payment.

What to verify:

  1. Your frontend displays a clear failure message and allows safe retry
  2. Your backend marks the payment as failed and avoids creating a successful order
  3. Your logs and monitoring capture the failure reason for troubleshooting

Test 3D Secure Authentication

Section titled “Test 3D Secure Authentication”

3D Secure (3DS) adds an authentication step between payment submission and final authorization when issuer verification is required.

Primary option: use the Payment Widget. It handles authentication screens and redirect behavior for you.

Secondary option: direct Checkouts API integration. This path requires PCI compliance and explicit onboarding/approval from SumUp. After processing a checkout, use the returned next_step object (url, method, optional payload, redirect_url, and mechanism) to continue the flow.

Successful 3D Secure Authentication Scenarios

Section titled “Successful 3D Secure Authentication Scenarios”

For Payment Widget integrations, onResponse can emit auth-screen when challenge authentication starts. After challenge completion, verify the final checkout result on your backend with Retrieve a checkout.

What to verify:

  1. Your frontend handles challenge redirects and return URLs correctly
  2. Your backend waits for the final authentication result before fulfillment
  3. Retry and timeout handling behaves correctly when users abandon the challenge
BrandCard NumberExpected Behavior
VISA4200 0000 0000 00423D Secure challenge is required.
VISA4200 0000 0000 00673D Secure challenge is required.
VISA4200 0000 0000 00183D Secure challenge is required.
VISA4200 0000 0000 00753D Secure challenge is required.
Mastercard5200 0000 0000 00153D Secure challenge is required.
Mastercard5200 0000 0000 00493D Secure challenge is required.
Mastercard5200 0000 0000 00643D Secure challenge is required.
Mastercard5200 0000 0000 00723D Secure challenge is required.
MAESTRO679 9998 9000 0006 00183D Secure challenge is required.
MAESTRO6773 6700 0911 48793D Secure challenge is required.
MAESTRO6 7034 2005 5456 50153D Secure challenge is required.
MAESTRO6759 8888 8888 88883D Secure challenge is required.
American Express343 4343 4343 43433D Secure challenge is required.
American Express375 9870 0000 00213D Secure challenge is required.
American Express375 9870 0016 98673D Secure challenge is required.
American Express371 4496 3539 84313D Secure challenge is required.
Diners / Discover36 2596 0000 00043D Secure challenge is required.
Diners / Discover6011 2087 0111 77753D Secure challenge is required.
Diners / Discover6559 9065 5990 65573D Secure challenge is required.
Diners / Discover36 4588 1111 11193D Secure challenge is required.
JCB3566 0023 4543 21533D Secure challenge is required.
JCB3569 9900 1009 59163D Secure challenge is required.
JCB3569 9900 1230 08763D Secure challenge is required.
JCB3569 9900 1230 08843D Secure challenge is required.
Dankort4571 9912 6271 89853D Secure challenge is required.
Dankort4571 9957 1262 84473D Secure challenge is required.
Dankort4571 9984 7027 96193D Secure challenge is required.
Dankort5019 9917 0704 47883D Secure challenge is required.
UnionPay6250 9470 0000 00973D Secure challenge is required.
UnionPay6250 9441 9672 52073D Secure challenge is required.
UnionPay6250 9496 4405 01733D Secure challenge is required.
UnionPay6250 9458 8276 81123D Secure challenge is required.
Bancontact Link6703 6461 7321 19933D Secure challenge is required.
Bancontact Link6703 6478 2371 87423D Secure challenge is required.
Bancontact Link6703 6188 4785 11993D Secure challenge is required.
Bancontact Link6703 6180 8422 19083D Secure challenge is required.

3D Secure Failure Scenarios

Section titled “3D Secure Failure Scenarios”

Use these cards to validate failed authentication and non-participation behavior.

These cards simulate:

  • Technical authentication errors
  • Cardholder not enrolled for 3D Secure
  • Card/issuer not participating in 3D Secure

What to verify:

  1. You display actionable error messaging for technical authentication failures
  2. You handle non-enrolled and non-participating cards without crashing
  3. Failed payments do not create successful order states in your system
BrandCard NumberExpected Behavior
VISA4012 0010 3746 1114Authentication fails due to a technical error.
VISA4012 0010 3714 1112Cardholder is not enrolled for 3D Secure.
VISA4532 4970 8877 1651Card or issuer does not participate in 3D Secure.
Mastercard5434 5800 0000 0006Authentication fails due to a technical error.
Mastercard5457 3500 7654 3210Cardholder is not enrolled for 3D Secure.
Mastercard5497 2608 4731 6287Card or issuer does not participate in 3D Secure.
MAESTRO6761 3010 0094 1201Authentication fails due to a technical error.
MAESTRO6761 3010 0094 6341Cardholder is not enrolled for 3D Secure.
MAESTRO6761 2577 0783 6567Card or issuer does not participate in 3D Secure.
American Express375 9870 0016 9875Authentication fails due to a technical error.
American Express375 9870 0016 9883Cardholder is not enrolled for 3D Secure.
American Express343 9230 9205 0144Card or issuer does not participate in 3D Secure.
Diners / Discover6510 0000 0000 1248Authentication fails due to a technical error.
Diners / Discover6011 0255 0026 5831Cardholder is not enrolled for 3D Secure.
Diners / Discover6011 4207 1174 6440Card or issuer does not participate in 3D Secure.
JCB3566 0077 7001 7510Authentication fails due to a technical error.
JCB3569 9900 1229 1497Cardholder is not enrolled for 3D Secure.
JCB3096 0233 6337 9943Card or issuer does not participate in 3D Secure.
Dankort5019 9968 9072 9079Authentication fails due to a technical error.
Dankort4571 9957 0066 7571Cardholder is not enrolled for 3D Secure.
Dankort4571 9933 1492 6574Card or issuer does not participate in 3D Secure.
UnionPay6250 9470 0000 0048Authentication fails due to a technical error.
UnionPay6250 9470 0000 0030Cardholder is not enrolled for 3D Secure.
UnionPay6250 9470 0000 0052Card or issuer does not participate in 3D Secure.
Bancontact Link6703 9957 3038 2544Authentication fails due to a technical error.
Bancontact Link6703 6495 1976 7306Cardholder is not enrolled for 3D Secure.
Bancontact Link6703 6495 1976 7555Card or issuer does not participate in 3D Secure.

Next Steps

Section titled “Next Steps”

Once you’ve thoroughly tested your integration with your sandbox merchant account and test cards:

  1. Switch back to your live account in the Dashboard
  2. Ensure your production credentials are properly configured
  3. Process a small real transaction to verify everything works as expected
  4. Monitor your first transactions closely to ensure proper payment processing

Footnotes

Section titled “Footnotes”

  1. Minor unit fractions refer to the smallest denomination of a currency, which is used for representing transaction amounts. For example, if a currency has two decimal places, like USD (dollars and cents), the minor unit is the cent, and an amount is represented as a whole number of cents ↩︎