Why the vocabulary is inconsistent, including inside the industry
Nobody owns these definitions. No registry certifies a company as a payment processor, no standards body adjudicates whether a business may call itself a payment service provider, and there is no penalty for using the words loosely. The card networks define a handful of terms in their operating regulations — acquirer, payment facilitator, sub-merchant — and everything else is convention.
Convention then diverged geographically. In Europe, payment service provider is close to a regulatory concept tied to licensing regimes; in the United States it is a marketing phrase. British and American usage of merchant acquirer differs over whether it includes the processing function or only the banking one. Sales staff at the same company will use two of these words interchangeably in a single call.
This page fixes the meanings for this site and explains what each type controls. The value is not taxonomic tidiness. It is that each type sits at a different point in the chain and can therefore solve only certain problems — asking a gateway to fix a reserve, or an orchestrator to lower interchange, is asking a layer for something it does not own.
The four parties in every card transaction
Start with the parties that must exist for a card payment to happen at all. These are structural, not commercial.
The issuer is the cardholder's bank. It issues the card, decides whether to approve each authorization, bears fraud losses on approved transactions in defined circumstances, and receives interchange. Merchants do not choose issuers and cannot negotiate with them.
The card network — Visa, Mastercard, American Express, Discover and the domestic schemes — routes messages between acquirer and issuer, publishes the operating rules, sets interchange and charges its own assessments. Networks do not sell acceptance and do not hold merchant funds. Visa and Mastercard set the price of the largest component of a merchant's card cost while having no commercial relationship with the merchant at all.
The processor is the technical operator that formats, transmits, clears and settles transactions. Processing is a function, not a legal status. Some acquirers process their own transactions, some outsource it, and some processors — like the issuer-side platforms FIS operates — never touch a merchant account. This is why processor and acquirer are persistently confused: the same company frequently does both.
The commercial layers sold on top
Everything below is a way of packaging access to an acquirer. None of these companies replaces the acquiring bank; they change who the merchant talks to, how quickly it can start, and who absorbs which risks.
- Payment service provider (PSP). Sells acceptance as a packaged product, typically bundling gateway, processing and, in the aggregator model, the merchant account itself. Adyen, Checkout.com, Nuvei, Stripe and PayPal all operate as PSPs, though with very different amounts of the chain owned in-house.
- Aggregator or payment facilitator (PayFac). Holds one master merchant account and boards businesses beneath it as sub-merchants. Registered with the networks, underwrites its sub-merchants itself, and is contractually liable for their losses. This is the model behind instant onboarding.
- Independent sales organization (ISO). Sells and services merchant accounts on behalf of an acquirer without holding the account or the risk. A merchant boarded through an ISO has a real dedicated merchant account; the ISO is the relationship, not the counterparty.
- Payment gateway. The authorization and tokenization layer connecting a merchant's checkout or terminal to a processor. Authorize.net and NMI are gateways sold largely through resellers. A gateway alone cannot accept money; something with a merchant account is required underneath.
- PayFac-as-a-service. Infrastructure that lets a software company monetize payments for its customers without registering as a facilitator or absorbing the full risk. Finix, Payrix, Rainforest and Moov sell versions of this, and the versions differ substantially in how much liability the software company retains.
- Payment orchestrator. A routing and analytics layer above multiple processors, used by merchants running more than one provider to manage authorization rates, cost and redundancy. Spreedly and Pagos operate here. Orchestration adds no acceptance capability of its own.
- Merchant of record. A company that becomes the legal seller of the product, taking on the transaction, the tax obligation and the chargeback liability. Paddle operates this way. It is the opposite end of the spectrum from an ISO: maximum transferred obligation, minimum merchant control.
One company, several labels
The single most misleading assumption in payments is that these categories are mutually exclusive. They are functions, and large companies accumulate them.
| Company | Functions it performs |
|---|---|
| Stripe | Payment service provider, payment facilitator, gateway, acquirer via bank partners |
| North | Merchant acquirer, ISO, payment facilitator, gateway, point-of-sale provider |
| Checkout.com | Acquirer, PSP, gateway, card issuer processor, electronic money institution |
| Adyen | Licensed bank, acquirer, PSP, gateway |
| Global Payments | Merchant acquirer, processor, payment facilitator, point-of-sale software vendor |
| Helcim | ISO and merchant services provider, PSP, point-of-sale software vendor |
Read that table as a warning about comparison. Two companies can both be accurately described as payment service providers while differing on the question that decides a merchant's experience: whether the merchant ends up with an account in its own name. Adyen holds its own banking license and is a principal network member in its licensed markets. Stripe reaches the networks through partner acquirers and boards most customers as sub-merchants. Both statements are true; the merchant outcomes are not the same.
The types that are not about cards at all
A large share of the payments industry never touches a card transaction, and applying card vocabulary to it produces nonsense. Six further types recur.
Bank rails and payment operations providers move money over ACH, direct debit, wires and real-time systems, and supply the ledgering and reconciliation tooling around them. Dwolla, GoCardless and Modern Treasury sit here. Their economics are per-transfer rather than percentage-of-value, which is why they displace cards for large-ticket recurring collection.
Business-to-business AP and AR automation platforms — BILL, Tipalti, Melio, Corpay — solve the invoice, the approval workflow and the reconciliation rather than the authorization. The payment is the last and easiest step.
Subscription billing platforms such as Chargebee and Recurly manage plans, proration, dunning and revenue recognition, and sit above whichever processor the merchant uses. Fraud and risk platforms like Forter sit inside the authorization path and are typically priced against the loss they claim to prevent. Bill payment and EBPP providers such as InvoiceCloud and Paymentus serve billers with recurring, non-discretionary obligations. Buy now, pay later providers including Affirm and Klarna are lenders that settle the merchant in full and retain the credit risk themselves.
Finally, freight audit and payment providers such as Cass Information Systems, and stablecoin infrastructure providers such as BVNK, are payments companies by function and nothing else on this page by structure. Neither can be evaluated with card vocabulary.
Three questions that beat the taxonomy
Categories are a map, and the map is coarser than the territory. When a company's type is genuinely unclear, three questions resolve it faster than any definition.
- Whose name is on the merchant account? If it is the business's own, it has a dedicated account and an acquirer that underwrote it. If it is the provider's, the business is a sub-merchant and the provider is operating as a facilitator, whatever it calls itself.
- Who absorbs the loss on an unrecoverable chargeback? The answer identifies the risk-bearing party in the chain, which is the party whose decisions will actually govern the account.
- Who can move the transaction to a different processor, and how hard is it? If card credentials are tokenized in a vault the merchant controls or can port, the provider is replaceable. If the tokens live with the provider, the merchant's flexibility is a contractual matter rather than a technical one.
The mistake most buyers make is to select a type first and a company second — deciding they want a payment facilitator, or an orchestrator, before establishing what problem is being solved. The type follows from the constraint: category and underwriting appetite first, then risk tolerance and cash-flow needs, then the layer that addresses them.
Frequently asked questions
What are the main types of payment companies?
The structural types are card networks, issuers, acquirers and processors, which are the four parties required for a card transaction to complete. The commercial types sold on top are payment service providers, aggregators and payment facilitators, independent sales organizations, gateways, PayFac-as-a-service platforms, orchestrators and merchants of record. Separately there are non-card types: bank rails and ACH providers, business-to-business AP and AR automation, subscription billing platforms, fraud and risk decisioning, bill payment and EBPP, buy now pay later lenders, freight audit and payment, and stablecoin settlement infrastructure.
What is a payment service provider?
A payment service provider, or PSP, sells payment acceptance as a packaged product, typically bundling the gateway, the processing connection and often the merchant account itself into a single contract and a single price. In Europe the term is tied to regulatory licensing regimes; in the United States it is a marketing description with no legal definition. The important variable is not the label but whether the PSP gives the merchant a dedicated merchant account in its own name or boards it as a sub-merchant under the PSP's master account.
Is a payment processor the same as an acquirer?
No, although the same company often performs both roles. An acquirer is a licensed financial institution that holds the merchant account, sponsors the merchant into the card networks, and carries the financial liability if the merchant fails to deliver on a sale. A processor is the technical operator that formats, transmits, clears and settles transactions, and processing can be done by the acquirer itself, outsourced to a third party, or performed on the issuing side where no merchant account is involved at all.
What is the difference between a PayFac and an ISO?
A payment facilitator holds one master merchant account and boards businesses beneath it as sub-merchants, underwrites them itself, and is contractually liable to the acquirer for their losses. An independent sales organization sells and services merchant accounts on behalf of an acquirer but does not hold the account or carry the risk, so each merchant it boards receives a dedicated merchant account in its own name. The practical difference for the merchant is onboarding speed against account ownership and documented terms.
Can one company be more than one type of payment company?
Almost all large payments companies are several types at once, because these are functions rather than exclusive categories. Stripe operates as a payment service provider, a payment facilitator and a gateway while reaching the networks through partner acquiring banks; North operates as an acquirer, an ISO, a facilitator, a gateway and a point-of-sale vendor. This is why a company's self-description is a weak basis for comparison, and why the useful questions are whose name is on the merchant account and who absorbs the loss when a chargeback cannot be recovered.