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Who should use this guideThis guide is intended for merchants who:
  • Use Payrails as a payment orchestrator
  • Use NMI to accept card, Apple Pay, and Google Pay payments
NMI is a server-to-server connector with no hosted payment page and no redirect flow for cards. Your shopper enters card details directly in your checkout through the Payrails SDK’s secure fields, or pays with Apple Pay or Google Pay, and payment details go directly to the NMI API.

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Create and configure an NMI integration in Payrails

Follow these steps to set up NMI:
  1. Log in to the Payrails portal.
  2. Go to Settings → Integrations → Payments.
  3. Select Add instance to create a new NMI integration configuration.
  4. Select the workspaces where this integration should be available.
About workspacesWorkspaces determine where this integration is available. They let you isolate provider setups by region or business line, or share the same configuration across multiple workspaces.

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Step 2: Choose the provider

Select NMI and continue to the next step. Payrails provider selection set to NMI

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Step 3: Configure your NMI integration

What you’ll need from NMIBefore you begin, make sure you have access to your NMI Merchant Portal and the following:
  • Host—the NMI gateway hostname for your account (for example secure.nmi.com, or a white-labeled domain if your NMI account is resold under a different brand)
  • API Key—a private security key, used to authorize every payment and maintenance call
  • Webhook Signing Key (optional but recommended)—used to verify that notifications genuinely come from NMI

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Integration instance name

An integration instance is a specific payment provider setup in Payrails. You can create multiple instances for each provider based on region, currency, or business needs. Choose a clear, consistent name, since it’s used in routing.
In Payrails
  • Enter an Instance name for your integration.
Payrails integration instance name field for NMI

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Account details—Host

In Payrails
  • Enter the Host field with your NMI gateway hostname (for example secure.nmi.com, or your white-labeled domain).
Payrails host field for the NMI gateway hostname The NMI gateway is frequently white-labeled or resold, so no single fixed sandbox or production host applies—use the hostname provided for your specific NMI account.

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API Key

In NMI
  • Log in to the NMI Merchant Portal.
  • Go to Settings → Security Options → Security Keys → Private Security Keys.
NMI Merchant Portal private security keys section
  • Select Add a New Private Key to retrieve or generate your API Key.
NMI Merchant Portal dialog for adding a new private key In Payrails
  • Paste the value into the API Key field.
Payrails API Key field for NMI
Store your API Key securely. It is sent as a static Authorization header on every request and is the only credential required to authorize payments.

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Webhook Signing Key

In NMI
  • Go to Settings → Webhooks → Endpoints → Create.
  • Add an endpoint pointing at the Payrails notification URL (copied after saving your NMI configuration—see Configure notifications below).
NMI webhook endpoint creation form NMI webhook endpoint pointing at the Payrails notification URL NMI webhook endpoint event selection
  • Select the events to be notified on.
  • Note the signing key generated for this endpoint.
In Payrails
  • Paste the value into the Webhook Signing Key field.
Payrails Webhook Signing Key field for NMI Store your webhook signing key securely. Payrails uses it to verify that notifications genuinely come from NMI.

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Payment methods

In Payrails
  • Under Payment methods, enable Card, Apple Pay, and/or Google Pay as needed. Each has its own configuration block.
Apple Pay requires additional setupEnabling Apple Pay on the NMI provider config alone is not enough—you also need a valid Apple Pay configuration (certificate or merchant identity) set up on the Payrails side under Apple Pay settings for your workspace.

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Enable the integration

In Payrails
  • Select Save account to save the configuration and enable the integration.
  • The Enabled status confirms that the NMI integration is active.
Your NMI integration is now ready to process payments.

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Next steps

  1. Run a test payment in test mode using an NMI test card:
    • Visa: 4111 1111 1111 1111, any near-future expiry, any three-digit CVV.
  2. Verify that:
    • The payment appears in your NMI Merchant Portal.
    • The payment status updates correctly in Payrails.
  3. Once verified in test mode, repeat the setup in live mode.
Continue to: Test a payment
Last modified on September 28, 2026