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NMI (Network Merchants Inc.) is a payment gateway provider offering secure card processing solutions for merchants worldwide. NMI provides flexible payment processing with extensive integration options and support for multiple payment types.

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Setup

Before you configure the connector, sign up for an NMI test account. NMI offers two account types with different sign-up processes - see Test accounts for details on each and how to sign up.

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Connector configuration

After signing up with NMI, you can configure the connector in Gr4vy using one of the following methods:
  • Flow - Configure payment routing rules through your Gr4vy dashboard
  • API integration - Specify the payment_service_id when creating transactions to explicitly route payments to this connector

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Credentials

Configure the following credentials in the Gr4vy dashboard, which are obtained from your NMI administrator portal:
  • API Key - Your NMI security key, found in the NMI administrator portal under Options → Settings → Security keys
  • Use the dedicated NMI Sandbox endpoint (sandbox.nmi.com) - Turn this on if the preceding API Key is a security key from a self-service Sandbox account. Leave it off (the default) if the API Key is from a Standard Test Merchant Account. Turning this on routes the connection to sandbox.nmi.com instead of NMI’s main gateway. Learn more about NMI test accounts.
Using the wrong setting for your account type causes NMI to decline every transaction. If your security key is from a Standard Test Merchant Account, leave this toggle off. If it is from a self-service Sandbox account, turn it on.

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Capabilities

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Supported countries

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Supported currencies

This is a closed-loop connector. Some failover scenarios are limited. For details, see Open-loop versus closed-loop.

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Integration

To accept card payments with NMI, use one of Gr4vy’s client-side integration methods to securely collect card details. Due to PCI compliance requirements, card data should never be sent directly to your servers. You can integrate using:
  • Embed - A pre-built, customizable payment form that handles the complete payment flow
  • Secure Fields - Embed card input fields for building custom payment forms while maintaining PCI compliance
  • Mobile SDKs - Native SDKs for iOS, Android, React Native, and other platforms
These methods handle card data collection and tokenization. Once the card details are collected and tokenized, create a transaction through the Gr4vy API, which routes the payment to your configured NMI connection based on your Flow rules or explicit payment_service_id parameter.

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Testing

If you test against a self-service Sandbox account (sandbox.nmi.com), NMI applies processor-level restrictions that do not apply to a Standard Test Merchant Account. These restrictions come from NMI, not from the Gr4vy connector, but they can look like connector issues if you do not expect them. See Test accounts for background on the difference between the two account types.
  • Test cards only - NMI only accepts a specific set of test card numbers on a Sandbox account. Check the documentation in your NMI Sandbox account for the current list of supported test cards.
  • Receipt emails - Transaction receipt emails can only be delivered to the email address associated with your NMI Sandbox account. Emails addressed to any other recipient are not delivered.
  • No custom descriptors - Custom statement descriptors are not applied to transactions processed through a Sandbox account.
These restrictions do not apply to a Standard Test Merchant Account.

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Test accounts

NMI offers two kinds of test accounts, and they are not interchangeable:
  • Standard Test Merchant Account - runs on NMI’s main gateway at secure.networkmerchants.com. An NMI Partner provisions this account for you, so contact your NMI Partner or sales representative to request one.
  • Sandbox account - runs on a dedicated sandbox at sandbox.nmi.com. NMI provides self-service sign-up for this account type. To sign up, visit the sign-up page and create an account.
Each account type has its own security key, and a security key issued for one endpoint does not work on the other. Keep track of which type of account you have. When you configure the connector’s credentials in Gr4vy, your account type determines whether you turn on the Use the dedicated NMI Sandbox endpoint (sandbox.nmi.com) setting. Turn it on for a Sandbox account API key, and leave it off for a Standard Test Merchant Account API key. Choosing the wrong setting for your account type causes NMI to decline every transaction, so this is the detail to get right when you configure credentials. This setting is unrelated to Gr4vy’s production or sandbox environment. Both NMI account types described here are test accounts, regardless of whether this toggle is on or off. The two account types also differ during testing - see Testing for the restrictions that apply to a Sandbox account.