How to Set Up the NMI Payment Integration in Sparkforge

NMI (Network Merchants Inc.) is a payment gateway that handles credit, debit, and eCheck transactions across web, mobile, and POS. Sparkforge supports NMI on order forms, invoices, and Text2Pay link payments.

What NMI brings to Sparkforge checkouts

• Multi-currency support across credit and debit card payments
• Tokenization and encryption for stored cardholder data
• AVS and CVV fraud checks
• Customizable checkout look-and-feel
• Recurring billing and subscription management
• Customer vault for stored payment methods
• Reporting and analytics on transactions

Step 1: Pull your three NMI keys

You need three values from your NMI merchant account:

• Gateway ID
• Security Key
• Public Key

For the Gateway ID, sign in to your NMI merchant account, open Settings > Account Information, and copy the Gateway ID. NMI's documentation covers Security Key and Public Key generation if you don't have them yet.

Step 2: Connect NMI in Sparkforge

1. In your sub-account, go to Payments > Integrations.
2. Find NMI and paste the Gateway ID, Security Key, and Public Key.
3. Click Save.

Upgrade to Funnels v2 — the integration depends on it.

Step 3: Enable 3DS (added September 2025)

1. Enroll Payer Authentication 2.0 inside your NMI account.
2. Confirm the service status reads Active.
3. Generate a Checkout Public Key for 3DS in the NMI Merchant Portal.
4. Add the 3DS Checkout Public Key to your Sparkforge integration.

Where NMI processes payments

NMI handles order forms (one-step, two-step, one-click upsells), invoices, and Text2Pay links. Calendars, SaaS, and memberships still process through Stripe even when NMI is the default.

Default gateway when multiple are connected

If you have Stripe, Authorize.net, or NMI connected together, Sparkforge requires you to pick one as the default for order form payments. PayPal can run alongside any of them as a separate payment method.

Subscription statuses on NMI

Retry logic

If a recurring payment fails, Sparkforge retries twice at 24-hour intervals. The status stays Unpaid while retries run. If a future payment succeeds, the subscription returns to Active. If every retry fails through the end of the schedule, status moves to Expired.

Reporting

All NMI transactions log to Payments > Transactions. Subscriptions live under Payments > Subscriptions. Triggers and attribution on order forms behave the same as with Stripe.