What Does a Payment Gateway Do?
A payment gateway handles the technical communication between your checkout page and the banking network. When a customer clicks "Pay," the gateway:
Captures Payment Data
Securely collects card number, expiry, CVV, and billing details through hosted fields or an API. The data is encrypted in transit.
Sends to Acquiring Bank
Forwards the encrypted transaction to your merchant acquiring bank, which communicates with the card network (Visa, Mastercard).
Receives Authorization
The issuing bank (customer's bank) approves or declines. The gateway returns this response to your checkout in real time — typically under 2 seconds.
Settles Funds
After authorization, the gateway initiates settlement — the actual movement of funds from the customer's bank to your merchant account. Settlement typically takes 1-3 business days.
Payment Gateway vs. Payment Processor
These terms are often used interchangeably, but they're distinct:
| Payment Gateway | Payment Processor | |
|---|---|---|
| Function | Technical data transmission | Actual fund movement |
| Analogy | The card terminal | The bank behind it |
| Examples | NMI, Authorize.net | First Data, TSYS, WorldPay |
In practice, many modern companies (Stripe, Adyen, Square) combine both functions — they're both the gateway and the processor. But understanding the distinction matters when you're evaluating payment infrastructure.
Payment Gateway vs. Payment Orchestration
This is the more important distinction for scaling businesses:
| Payment Gateway | Payment Orchestration | |
|---|---|---|
| Processors | One | Multiple |
| Routing | Fixed | Intelligent (rules + data-driven) |
| Failover | None | Automatic retry on alternative processor |
| Lock-in | High | Low |
| Best for | Early-stage businesses | Scaling businesses ($100K+/mo) |
When to upgrade
A single gateway works fine until you hit scale. Signs you've outgrown a single gateway: approval rates below 90%, you've experienced processor downtime, you sell internationally, or you're in a high-risk vertical.
How to Choose a Payment Gateway
Key factors to evaluate:
Supported Payment Methods
Does it support the methods your customers want? Beyond cards, consider:
- Digital wallets (Apple Pay, Google Pay)
- Buy Now Pay Later (Klarna, Afterpay)
- Local payment methods (iDEAL, Bancontact, PIX)
- Cryptocurrency
Pricing Structure
Gateway fees vary significantly:
- Flat rate: Simple but often expensive (e.g., 2.9% + $0.30)
- Interchange plus: Transparent, better for high volume
- Tiered: Opaque, generally worst value
Developer Experience
If you're building custom checkout flows:
- API documentation quality
- SDK availability (JavaScript, mobile)
- Webhook reliability
- Sandbox/testing environment
- PCI compliance approach (hosted fields vs. API-direct)
Geographic Coverage
If you sell internationally:
- Local acquiring in your key markets (reduces cross-border fees)
- Multi-currency settlement
- Local payment method support
Common Payment Gateways
Full-Stack (Gateway + Processor)
- Stripe — Developer-first, excellent docs, broad feature set
- Adyen — Enterprise-grade, strong international coverage
- Square — Best for omnichannel (online + in-store)
- Braintree (PayPal) — Strong PayPal/Venmo integration
Gateway-Only
- NMI — Processor-agnostic, popular with high-risk merchants
- Authorize.net — Legacy but widely supported
- USAePay — Common in high-risk and CBD verticals
Don't marry your gateway
The biggest mistake ecommerce businesses make is building their entire stack around one gateway. Use tokenization and, ideally, a payment orchestration layer so you can add, remove, or switch gateways without touching your checkout code.