What is a payment gateway and how does it work? (2026 guide)

Key Takeaways

• A payment gateway is the technology that captures your customer's payment details at checkout, encrypts them, and sends them for approval, all in a few seconds.

• Understanding how a payment gateway works helps you choose one that fits your business, your customers, and the markets you sell into.

• Airwallex Payments acts as a payment gateway, processor, and acquirer in one. With Airwallex, you can accept 160+ local payment methods in 180+ currencies.

If you're wondering how a payment gateway works, it’s essentially the technology connecting your customer's checkout to the financial institutions that approve and process the payment.

It securely captures payment details, encrypts the information, and sends it through the payment network to authorise the transaction, usually in just a few seconds.

In this guide, we'll explain what a payment gateway does, how the payment process works from checkout to approval, and what to look for when choosing one for your business.

 If you're looking for a comparison of specific payment gateways, see our guide to payment gateways in Singapore.

What is a payment gateway?

A payment gateway is the technology that lets your business accept payments from customers. It collects payment details at checkout, encrypts them, and sends them to the relevant financial institutions for approval.

The term is most commonly used for online payments, but it applies to in-person payments too. A card terminal at a physical store is also a form of payment gateway.

What a payment gateway does

Most people think of a payment gateway as a checkout form. It's more than that. Behind the visible interface, the gateway handles several functions at once:

• Encryption: When a customer enters their payment details, the gateway encrypts that data before it moves anywhere. This protects both the customer and your business, and keeps the transaction in line with Payment Card Industry Data Security Standard (PCI DSS) requirements.

• Tokenisation: Instead of storing actual card details, the gateway replaces them with a unique string of characters called a token. The real data sits in a secure vault. The token is what moves through your systems for future transactions.

• Fraud detection: Most gateways run real-time checks on each transaction — looking at patterns, verifying card details, and flagging anything that looks suspicious before it's approved.

• Data and reporting: Gateways record transaction outcomes, which gives you visibility into approval rates, chargebacks, and declined payments.

Is a payment gateway the same as a payment processor?

No, though many providers bundle both services together, which can cause confusion.

The gateway is the front end: it collects and encrypts your customer's payment details and passes them on. The payment processor is the back end: it routes that information between the card networks (like Visa or Mastercard), the customer's bank, and your merchant account to move the money.

In practice, many payment providers act as both the gateway and the processor, so you don't need to manage them separately. For a detailed breakdown of how the two differ, see our guide on payment gateway vs payment processor.

How does a payment gateway work?

When a customer pays on your website, the gateway runs through a sequence of steps in the background. The whole process takes a few seconds. Here's what happens at each stage:

Step 1: Customer submits payment

The customer reaches your checkout page, selects a payment method (a credit card, PayNow, GrabPay, or another option you support) and confirms the payment. At this point, the gateway captures their payment details.

Step 2: Encryption and secure transmission

The gateway immediately encrypts the payment data. Your servers never hold raw card numbers. The encrypted details are passed to the payment processor.

Step 3: Authorisation request

The payment processor forwards the transaction details to the relevant card network (for example, Visa or Mastercard) or payment rail (for example, PayNow's Fast And Secure Transfers system).

The card network then sends an authorisation request to the customer's issuing bank.

Step 4: Approval or decline

The customer's bank checks whether the funds are available and whether the transaction looks legitimate.

It sends back an approval or decline response through the same chain: bank → card network → payment processor → gateway.

Step 5: Response displayed to customer

The gateway receives the response and displays the result on your checkout page. If approved, the customer sees a confirmation. If declined, they're prompted to try another payment method.

Step 6: Settlement

Approval doesn't mean the money moves immediately. Settlement (which refers to the actual transfer of funds from the customer's bank to your merchant account) typically happens within one to two business days, depending on your provider and the payment method used.

4 types of payment gateways

There are four main types of payment gateways. The difference between them comes down to where the customer enters their payment details and how much control you have over that experience.

Here’s a quick overview:

1. Hosted payment gateway

With a hosted gateway, your customer leaves your website to complete the payment. When they click "Pay Now", they're redirected to a page hosted by the payment service provider (PSP). Once the payment is confirmed, they're sent back to your site.

This is the simplest option to set up and maintain. The PSP handles all the security and compliance requirements on their end. The trade-off is that you hand over control of the checkout experience (including your branding and layout) to the provider's page.

2. Self-hosted payment gateway

With a self-hosted gateway, the checkout form lives on your own website. Customers enter their payment details without leaving your site, which keeps the experience consistent with your branding.

The payment details are still processed by a PSP behind the scenes; the form just sits on your side. This gives you more control over how the checkout looks and feels, but requires more technical setup than a hosted option.

3. API-hosted payment gateway

An Application Programming Interface (API) gateway connects your checkout directly to a PSP's payment processing system. Everything happens on your website or app; the customer never sees a third-party page or form.

This approach gives you the most control and can be tailored precisely to your checkout flow. It requires developer resources to build and maintain, but it's the preferred choice for businesses that want a fully custom payment experience.

4. Local bank integration

A local bank integration redirects the customer to their bank's own platform to complete the payment. In Singapore, this is common with bank-linked payment methods.

DBS PayLah! is one example. The customer is taken to the DBS interface to authorise the payment, then returned to your site once it's confirmed.

Airwallex Payments lets you choose what works best for your business, from hosted checkout and low-code integrations to fully custom API solutions.

Payment methods Singapore businesses should support

In Singapore, a good payment gateway should support PayNow (the dominant real-time bank transfer method), major card networks, GrabPay for regional customers, SGQR for in-person sales, and BNPL options like Atome for retail.

If you sell internationally, look for support for Alipay, WeChat Pay, and other market-specific methods.

For a full breakdown by market and use case, see our guide to eCommerce payment gateways.

Yes. I think a small table works better than the current paragraphs, because there are a few distinct concepts you're explaining: what regulates payment providers, the licence types, and what businesses should check.

I'd structure it like this:

Payment gateways and MAS regulation in Singapore

Payment service providers in Singapore are regulated by the Monetary Authority of Singapore (MAS) under the Payment Services Act (PS Act), which came into effect in January 2020.¹

If you're choosing a payment gateway, here's what to know:

Why does this matter? Choosing a licensed provider means you're working with a business subject to MAS requirements around areas such as safeguarding customer funds and managing risks. It gives you an added layer of protection if something goes wrong.

Benefits and limitations of payment gateways

Understanding what a payment gateway gives you (and where its limits are) helps you choose the right provider and set realistic expectations.

Benefits

• Accept more payment methods. Take card payments, digital wallets, and local payment methods from customers in Singapore and overseas, rather than relying only on bank transfers or cash.

• Protect your customers' data. Gateways encrypt and tokenise sensitive payment data, reducing the amount of cardholder information stored on your systems and helping with PCI DSS compliance.

• Get payments processed in seconds. Most transactions are authorised in real time, so customers get an immediate response and you can see which payments were approved or declined.

• Track your payment performance. Most gateways provide dashboards showing things like approval rates, failed payments, and chargebacks, helping you spot issues at checkout.

Limitations

• Fees can add up. Transaction fees are standard, and some providers also charge monthly fees, setup costs, or fees for specific payment methods. See our guide to payment gateway fees for a closer look.

• Integration takes some work. You'll need to connect the gateway to your website or app, and the complexity depends on the integration you choose. Hosted gateways are generally quicker to set up, while API integrations require more developer resources.

• Payment method coverage varies. Not every gateway supports PayNow, GrabPay, BNPL, or other local payment methods. Check that your provider supports the methods your customers actually use.

• Chargebacks can still happen. Customers can dispute transactions, which may result in funds being reversed. Fraud detection tools can help reduce the risk, but they can't eliminate it.

Why Singapore businesses choose Airwallex as their payment gateway

If you're looking for a payment gateway, Airwallex lets you accept 160+ local payment methods across 180+ countries. You can accept cards, wallets, bank-based payment methods, and other local options without managing separate payment integrations.

On top of that, here’s what you get with Airwallex: 

Improve acceptance rates with Optimize 360

Airwallex's Optimize 360 uses machine learning to help more legitimate transactions go through while reducing fraud. It combines tools such as adaptive payment routing, intelligent retries, network tokenisation, and smart 3DS authentication to improve authorisation rates and reduce failed payments.

Integrate with your existing checkout

Airwallex offers several ways to integrate payments, including a Payments API, hosted Checkout, plugins for platforms such as Shopify and WooCommerce, and Payment Links. Whether you have a developer team or want a simpler setup, you can choose the integration that fits your business.

Get paid and manage your funds in one place

Airwallex connects payment acceptance with multi-currency accounts, so you can collect and hold funds in multiple currencies instead of automatically converting everything to SGD. You can then use those balances to pay suppliers, fund cards, or make international transfers.

Frequently asked questions (FAQs)

What is a payment gateway in simple terms?

A payment gateway is the technology that collects your customer's payment details at checkout, encrypts them, and sends them for approval, all in a few seconds. Think of it as the digital equivalent of a card terminal at a physical store counter.

How does a payment gateway work step by step?

When a customer pays, the gateway captures their details and encrypts them. It passes the encrypted data to the payment processor, which routes it to the card network and then the customer's bank for approval. The bank sends back an approval or decline, and the gateway displays the result on your checkout page. Funds then settle into your merchant account, typically within one to two business days.

What is the difference between a payment gateway and a payment processor?

The gateway is the front end; it collects and encrypts payment details. The processor is the back end; it routes those details between card networks and banks to move the money. Many providers handle both, so you often don't need to manage them separately. For a full breakdown, see our guide on payment gateway vs payment processor.

Do payment gateways in Singapore need to be licensed?

Yes. Payment service providers operating in Singapore must hold a licence from the Monetary Authority of Singapore (MAS) under the Payment Services Act. You can verify any provider's current licence status on the MAS Financial Institutions Directory at mas.gov.sg.

How much does a payment gateway cost?

Costs vary significantly between providers and typically include a per-transaction fee, and sometimes a monthly fee or setup cost. Some providers also charge differently for local versus international payments. For a detailed breakdown, see our guide to payment gateway fees.

Which payment gateway is best for Singapore businesses?

The right gateway depends on your business model, the markets you sell into, and the payment methods your customers use. Airwallex is a strong option for businesses that sell across borders, as it combines a payment gateway with multi-currency accounts and global payouts in one platform. For a full comparison of providers, see our payment gateway Singapore guide.

Sources

1. mas.gov.sg/regulation/payments