NMI Payment Gateway — Features, Integrations & How It Works
NMI provides a white-label payment gateway used by thousands of ISOs, ISVs, and payment facilitators worldwide. This page covers the platform architecture, core features, integration options, and how NMI compares to alternatives like Authorize.Net and Stripe.
What Is the NMI Payment Gateway?
NMI (Network Merchants, Inc.) operates a multi-processor payment gateway designed primarily for B2B distribution. Unlike consumer-facing processors like Square or Stripe, NMI works behind the scenes — ISOs and resellers white-label the gateway under their own brand and offer it to their merchants. This architecture makes NMI one of the most widely deployed gateways in North America, even though many merchants do not know they are using it.
The gateway handles credit and debit card processing, ACH/eCheck, tokenized recurring billing, Level 2/3 data for B2B transactions, and supports 125+ shopping cart integrations out of the box. For a detailed overview of the company, see What Is NMI?
Core Gateway Features
Virtual Terminal
Browser-based transaction processing for phone and mail orders. No hardware needed.
Customer Vault
PCI-compliant token storage for recurring billing and card-on-file transactions.
Developer API
RESTful API with webhooks, SDKs for PHP, .NET, Java, and mobile frameworks.
White Label
Full rebranding for ISOs: custom domain, logo, colors, and merchant-facing UI.
Level 3 Data
Enhanced data fields for B2B and government transactions to qualify for lower interchange.
Multi-Currency
Process in 130+ currencies with dynamic currency conversion support.
Read our full breakdown in the NMI Features article.
Gateway Architecture
NMI sits between the merchant’s point of sale and the acquiring processor. When a card is swiped, dipped, tapped, or keyed in, the transaction data flows through the NMI gateway, which encrypts it, applies fraud filters, routes it to the appropriate processor, and returns the authorization response to the merchant in real time.
NMI connects to multiple acquiring processors simultaneously, which means merchants are not locked into a single processing bank. ISOs can route transactions to different acquirers based on card type, volume, or risk profile — a key advantage over single-processor gateways.
Integration Options
| Method | Best For | PCI Scope |
|---|---|---|
| Hosted payment page (HPP) | Quick setup, low technical skill | Minimal (SAQ A) |
| Collect.js (JavaScript tokenizer) | Custom checkout without handling card data | SAQ A-EP |
| Direct API post | Full control, custom payment flows | SAQ D (highest) |
| Shopping cart plugins | WooCommerce, Magento, Shopify, etc. | Varies by plugin |
| Mobile SDKs | iOS and Android apps | Varies |
See our NMI Integrations guide for setup instructions and code examples.
NMI vs Competitors at a Glance
| Feature | NMI | Authorize.Net | Stripe |
|---|---|---|---|
| Gateway model | White-label, multi-processor | Single-brand, Visa-owned | Full-stack processor |
| Best for | ISOs, resellers, high volume | SMBs, established merchants | Developers, SaaS, startups |
| Cart integrations | 125+ | 100+ | Custom via API |
| Recurring billing | ✓ Customer Vault | ✓ ARB | ✓ Billing API |
| White-label | ✓ Full | — | — (Stripe Connect) |
| Level 3 data | ✓ | ✓ | ✓ |
| Multi-processor | ✓ | — | — |
Deep-dive comparisons: NMI vs Authorize.Net | NMI vs Stripe
Pricing
NMI does not publish a single price list. Pricing depends on your ISO or reseller agreement, transaction volume, card-present vs. card-not-present mix, and which features you use. Most agreements follow interchange-plus or tiered models. See our NMI Pricing breakdown for typical fee structures.
Getting Started
To begin using NMI, you need an account provisioned through an ISO, reseller, or payment facilitator. Once approved, you receive gateway credentials and can access the NMI Login portal immediately. For small businesses, see our NMI for Small Business guide.
Is NMI a payment processor or a gateway?
NMI is a payment gateway, not a processor. It routes transactions to acquiring processors. This multi-processor architecture lets ISOs choose their preferred acquirer.
Can I use NMI without an ISO?
NMI primarily distributes through ISOs and resellers. Individual merchants typically get access through their payment provider rather than signing up with NMI directly.
Does NMI support ACH payments?
Yes. NMI supports ACH/eCheck processing alongside card transactions. This is configured at the account level by your ISO.