How payment gateways work and how to choose one

Payment gateways are one of those parts of running an online store that are invisible when they work and extremely visible when they do not. Understanding how a payment gateway processes a transaction, what the fees actually cost you, and how to evaluate your options means you are making a decision based on real criteria rather than default choices. This article covers the full picture, from the mechanics of how a transaction flows to what to look for when you are choosing a gateway for your store.

What is a payment gateway?

A payment gateway is the technology that authorizes and processes payment transactions between your customer and your store. When a customer enters their card details at checkout, the payment gateway encrypts that data, sends it to the card network for authorization, receives the approval or decline, and relays the result back to your store. The money then moves from the customer's bank to your merchant account, typically within one to three business days.

The gateway is distinct from the payment processor and the merchant account, though all three are part of the same transaction chain. In many modern payment solutions, particularly those designed for online stores, all three functions are bundled together into a single product. For most store owners, the practical question is not how to distinguish between gateway, processor, and merchant account, but whether the payment solution you choose handles transactions reliably, charges fees you can sustain, and supports the payment methods your customers expect to use.

How does a payment gateway process a transaction?

The journey from a customer clicking "pay" to the money arriving in your account involves more steps than most people realize, and each step happens within seconds.

Data capture and encryption

The customer enters their payment details on your checkout page. The payment gateway immediately encrypts this data so it cannot be intercepted in transit. The raw card numbers never reach your store's server. They go directly from the customer's browser to the gateway, which is why using a reputable payment gateway is one of the most important parts of keeping customer data secure.

Authorization request

The gateway sends the encrypted transaction data to the payment processor, which forwards it to the relevant card network. The card network routes it to the customer's issuing bank, which checks whether the customer has sufficient funds and whether there are any fraud flags on the transaction. The bank sends back an approval or decline.

Authorization response

The approval or decline travels back through the same chain, from the issuing bank to the card network to the processor to the gateway, which delivers the result to your store's checkout in real time. If approved, the customer sees a confirmation. If declined, they are prompted to use a different payment method.

Settlement

Authorization confirms the funds exist and reserves them, but it does not move money immediately. Settlement is the process of transferring funds from the customer's account to your merchant account. Most payment gateways batch settlements daily. The funds typically arrive in your bank account within one to three business days, depending on the gateway and your plan.

What fees does a payment gateway charge?

Payment gateway fees come in several forms, and understanding all of them matters when you are comparing options. Looking only at the transaction rate without accounting for the other fee types can lead to choosing a gateway that costs significantly more in practice than the headline rate suggested.

Transaction fees

The most visible fee is the per-transaction rate, typically expressed as a percentage of the transaction value plus a fixed cent amount. A common structure is something like 2.9% plus 30 cents per transaction. These fees are deducted automatically from each transaction before the remainder is deposited. On a $50 sale, a 2.9% plus $0.30 fee means you receive approximately $48.25.

Monthly fees

Some gateways charge a flat monthly fee for access to their service, regardless of transaction volume. This structure sometimes comes with lower per-transaction rates, making it more cost-effective for stores with consistent, higher transaction volumes. For stores with lower or inconsistent volume, a monthly fee adds cost without guaranteed benefit.

Chargeback fees

When a customer disputes a transaction with their bank, the resulting chargeback triggers a fee charged to your account, typically between $15 and $25 per chargeback, regardless of the outcome. This fee exists to cover the administrative cost of the dispute process. Stores in categories with higher dispute rates need to factor chargeback fees into their overall payment processing cost.

Currency conversion fees

If your store sells internationally and accepts payments in currencies other than your settlement currency, currency conversion fees apply. These vary by gateway and are sometimes not prominently advertised. For stores with significant international order volumes, this fee compounds quickly and is worth checking before committing to a gateway.

What payment methods should your gateway support?

Credit and debit cards remain the dominant payment method for online purchases, but the share of transactions completed through digital wallets and alternative payment methods has grown substantially. Research shows that checkout abandonment increases when a customer's preferred payment method is not available at the point of payment.

For most stores, the minimum coverage is major credit and debit cards across the major networks, plus at least one digital wallet option. For stores selling to younger demographics or in categories where mobile purchasing is common, digital wallet support is particularly important. For stores offering higher-ticket items, buy now pay later integration has become an increasingly relevant consideration, which the article on buy now pay later for online stores covers in full.

How important is checkout security?

Security is not negotiable for payment processing. The two things to verify for any gateway you are considering are Payment Card Industry Data Security Standard compliance and secure data encryption. The Payment Card Industry Data Security Standard is a set of requirements that any organization handling card data must comply with. A gateway that meets these standards handles card data in a way that protects customers and reduces your liability as the store owner.

Secure data encryption ensures that information transmitted between your customer's browser and the payment gateway cannot be intercepted. A valid security certificate is required for any store accepting payments, and most reputable gateways require it as a condition of use. WEMASY stores include this as standard, so it is covered automatically without separate setup.

Beyond the technical standards, fraud detection tools built into the gateway add a layer of protection against fraudulent transactions. These tools check transaction patterns, flag suspicious activity, and in some cases apply additional verification steps for high-risk transactions. The sophistication of these tools varies by gateway and by plan level.

How do you choose a payment gateway for your online store?

Choosing a payment gateway is a decision with long-term implications. Switching gateways later is possible but disruptive, so taking the time to evaluate options properly before launching is worth it.

Start by mapping the transaction volume you realistically expect. If you are launching for the first time, use a conservative estimate. The fee structure that works best for a store processing $500 a month is often different from the one that works best at $10,000 a month. A gateway with no monthly fee but higher per-transaction rates tends to be more cost-effective at lower volumes. One with a monthly fee and lower transaction rates may cost less at higher volumes.

Check which payment methods each gateway supports, both now and in terms of their roadmap for adding new methods. Verify that the gateway integrates with your store without requiring custom development. Confirm where they operate, since some gateways are not available in every country and may not support settlement in your local currency. Read how they handle disputes and chargebacks, specifically what tools they offer to help you contest fraudulent chargebacks and what their response time is for merchant support.

What is the difference between hosted and integrated payment gateways?

A hosted payment gateway redirects customers to a separate payment page on the gateway's own domain to complete the transaction. After payment is processed, the customer is returned to your store. The advantage is that you never handle card data directly. The disadvantage is that the checkout experience breaks the visual continuity of your store, which some customers find disorienting and which can increase abandonment.

An integrated gateway keeps the customer on your store's checkout page throughout the transaction. The card details are captured within your checkout, encrypted by the gateway's technology operating within your page. The experience is seamless for the customer. The responsibility for PCI compliance is shared more actively between you and the gateway. Most modern e-commerce stores use integrated gateways because the checkout experience is significantly smoother.

How do payouts and settlement timing affect your cash flow?

Settlement timing, the time between a customer completing a purchase and that money arriving in your bank account, affects cash flow directly. Standard settlement times range from one to three business days for most established gateways. Some offer same-day or next-day payouts, often at a premium fee. Some hold funds for longer when an account is new or when transaction patterns trigger a risk review.

For brands that operate on tight margins or carry significant inventory, knowing exactly when funds settle matters for managing cash flow. A gateway that settles in two days means your money is accessible faster than one that takes three days, and that difference compounds across hundreds of transactions per month. Checking payout schedules and any conditions that trigger holds is a practical step before committing to a gateway, particularly at launch when every day of cash flow matters.

How WEMASY handles payments for your online store

WEMASY's e-commerce system integrates with leading payment gateways so your store can accept cards and digital wallet payments without requiring separate technical setup. Secure data encryption is included on every WEMASY store, which satisfies one of the core requirements for accepting payments online. The checkout flow is built to minimize abandonment, with a clean layout that supports the payment method options your customers expect.

For a full breakdown of what is included in each plan and which payment integrations are available, see the pricing page. For help understanding how checkout design affects conversion, the article on how to design a checkout page that reduces drop-off covers the layout and copy decisions that make a measurable difference.

Frequently asked questions