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We provide a lightweight API simulator that allows merchants and partners to test their integration with the Paymend API without processing real payments. The sandbox is designed to validate:
  • Request structure and mandatory fields
  • Authentication handling
  • Core payment flows (create, capture, refund, void, query)
  • Basic success and failure scenarios
The simulator does not process real transactions and, in this first version, does not persist payment state. Responses are mocked and limited to predefined behaviours. For example, the same payment id value is always returned for successful payment creation and all follow-up requests (capture, refund, void or query) must reference this same id.

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API environments

The following details should be used for testing your integration in sandbox:
EnvironmentBase URLNotes
Sandboxhttps://sandbox-api.paymend.comUse for testing only. Transactions are simulated.
Important: Always use your sandbox credentials when testing. Production credentials are separate and should be kept secure.

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Authentication

All API requests require a Bearer token in the Authorization header: 👉 To get your API token, just reach out to your Paymend sales representative. 
Authorization: Bearer <your_api_token>
  • Tokens are issued specifically for sandbox use.
  • Requests without valid authentication will return 401 Unauthorized.
  • Ensure you are using sandbox credentials when targeting the sandbox environment.

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How the simulator works

The sandbox returns simplified, deterministic responses:
  • A single payment id is used for all responses. Any request referencing a different payment id will fail with a HTTP error.
  • The simulator does not persist payment state. Dependent requests (capture, refund, void, query) always return a fixed success response regardless of payment history.
  • Partial captures and refunds are not supported in the simulator. Any specified amount values (eg. captureAmount, refundAmount) are ignored.
  • Mandatory fields defined by the API are enforced.
  • Basic validation (eg. on field types) is performed.
These behaviours are intentionally limited to simplify testing.

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Test cards

When creating payments in the sandbox, specific test card numbers determine simulated outcomes. The table below shows which card number and brand values can be passed in the paymentMethod object during payment creation to receive different status and failure object values in the response.
card.numbercard.brandstatusfailure.failureCode
4444444444440000VISAAUTHORIZED / CAPTURED*
5555555555550000MASTERCARDAUTHORIZED / CAPTURED*
4444444444440051VISAFAILEDINSUFFICIENT_FUNDS
5555555555550051MASTERCARDFAILEDINSUFFICIENT_FUNDS
*Whether you receive AUTHORIZED or CAPTURED will depend on the value passed in the captureNow field.

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Request examples

Click the links in the Endpoints section in the sidebar to see example requests for payment creation, capture, refund and void requests, as well as queries.

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Next Steps

Once your integration is working smoothly in sandbox:
  • Request production credentials from Paymend.
  • Update your base URL to the production endpoint.
  • Perform live transaction testing as needed.