Every time a card is swiped, tapped, or entered online, a payment processor is working in the background to validate the transaction, route the funds, and settle the payment within days. Payment processors are the infrastructure layer connecting merchants, card networks, and banks. Choosing the right payment processor can significantly affect a business's costs, checkout conversion rate, and global reach. This guide explains what payment processors do, how they differ from gateways, the main fee structures, and what to look for when choosing one.
What Is a Payment Processor?
A payment processor is a company that manages the transaction process between a merchant and the financial institutions involved in a payment. When a customer pays, the processor transmits the payment data to the card network (Visa, Mastercard), receives the authorization from the customer's issuing bank, and handles the settlement of funds to the merchant's account. Payment processors are distinct from payment gateways (which are the software interface connecting the merchant's system to the processor) — though many modern providers like Stripe and Square bundle both into a single product. Some processors also act as the merchant's acquirer, holding the merchant account.
How Payment Processing Works
A card transaction happens in three stages. Authorization: the merchant's system sends a request to the processor, which routes it to the card network and then to the customer's issuing bank. The bank approves or declines and sends back an authorization code in under two seconds. Capture: the merchant's system signals that goods/services have been provided, triggering the capture of the authorized funds. Settlement: at the end of the business day, captured transactions are batched and sent through the card network for settlement. The merchant typically receives funds 1–2 business days later, net of processing fees.
Payment Processing Fee Structures
Merchant fees are composed of three layers. Interchange fees are paid to the card-issuing bank — set by the card network and typically 0.5–2% of the transaction value, varying by card type and industry. Scheme fees are paid to the card network (Visa, Mastercard). The processor margin is the payment processor's revenue. These are often bundled into two pricing models: flat-rate pricing (e.g., Stripe's 2.9% + $0.30) simplifies cost but can be expensive at scale; interchange-plus pricing shows each component separately and is typically more cost-effective for higher-volume merchants.
Key Takeaways
- Payment processors handle authorization, capture, and settlement of card transactions.
- Flat-rate pricing is simpler; interchange-plus is cheaper for high-volume merchants.
- Modern payment facilitators like Stripe bundle gateway, processing, and acquiring.
- Processing fees have three components: interchange, scheme fees, and processor margin.
- Settlement typically takes 1–2 business days after a transaction is captured.
Top Platforms
| Platform | Category | Key Feature | |
|---|---|---|---|
| Stripe | Payment Processor | Best-in-class APIs for developers | View |
| Square | Payment Processor | In-person and online payments for SMBs | View |
| Adyen | Payment Processor | Enterprise-grade, 200+ payment methods | View |
| PayPal | Payment Processor | Widest global consumer recognition | View |
| Worldpay | Payment Processor | High-volume enterprise processing | View |
How to Choose a Platform
- Calculate total cost at your expected monthly volume — include interchange, scheme fees, and processor margin.
- For early-stage businesses, start with a payment facilitator (Stripe, Square) for instant onboarding.
- For high-volume merchants (>$1M/year), negotiate interchange-plus pricing directly.
- Verify the processor supports all payment methods your customers prefer.
- Check fraud tools and chargeback management — prevention saves more than it costs.
Frequently Asked Questions
What's the difference between a payment processor and a payment gateway?
A payment gateway is the software interface that securely transmits transaction data from the merchant to the processor. A payment processor handles the actual routing of funds between banks. Modern platforms like Stripe bundle both — you rarely need to think about them separately.
What is interchange and who sets it?
Interchange is the fee paid to the card-issuing bank on each transaction — it compensates the bank for credit risk, fraud losses, and cardholder rewards. Interchange rates are set by card networks (Visa, Mastercard) and vary by card type, merchant category, and geography.
How long does payment settlement take?
Typically 1–2 business days for card payments after the batch is submitted. Some processors offer next-day or instant settlement for an additional fee. Alternative payment methods (ACH, bank transfers) may take 2–5 business days.
Can a payment processor drop my business?
Yes. Payment processors can terminate merchant accounts for excessive chargebacks, fraud, prohibited business types, or policy violations. High-risk industries (gambling, adult content, firearms) often need specialist high-risk processors with different pricing and terms.
Related Guides
What Is Fintech? A Complete Guide to Financial Technology
Read Financial InfrastructureWhat Is Open Banking? APIs, PSD2, and the Future of Finance
Read Payments InfrastructureHow Payment Processors Work: A Guide to Modern Payments
Read Payments InfrastructurePayment Gateways vs Payment Processors: What's the Difference? (2026)
ReadIs your company in the directory?
Reach thousands of fintech professionals and investors exploring the Digital.Finance directory.
Get Listed