What are Payment Gateways?

A payment gateway is the service that carries payment details from a customer's checkout to the payment processor and returns the result to the merchant. It does for an online store what a card terminal does in a shop. The gateway does not move the money itself. The payment processor and the banks do that.

What a gateway does

1. The customer enters payment details on the merchant's site or app.
2. The gateway encrypts the details and sends them to the processor.
3. The processor asks the customer's bank or card issuer to authorize the payment.
4. The approval or decline travels back to the gateway.
5. The gateway tells the merchant, and the order can continue.

Gateways also tokenize card data, support PCI DSS requirements, and often include fraud checks. See payment security.

Types of gateway

• Hosted: the customer is redirected to the provider's payment page. It is easy to set up but moves the customer away from your site.
• Integrated: the payment form sits inside your own site or app. You control the experience and carry more of the build.
• API-based: your backend calls the provider's API directly. This gives the most control and needs the most engineering.

Payment integration

Integrating a gateway means connecting your platform to it through an API. A working integration usually covers creating the payment, showing it to the customer, receiving status updates by webhook, and reconciling orders against the provider's records. A sandbox lets a team test successful, failed and expired payments before going live.

Crypto payment gateways and fees

Crypto gateways are usually cheaper than cards, but less than the headline suggests. The Amboss comparison Crypto Payment Gateway Fees (June 2026) found that most major gateways land between 1% and 3% all-in once deposit, withdrawal and conversion costs are added. Cards charge 2.9% + $0.30 in the same comparison.

Amboss lists five cost items to compare: the deposit or processing fee, the withdrawal fee, the conversion spread, any fiat off-ramp markup, and token discounts or minimum balance rules. It also notes that many gateways hold merchant funds until withdrawal, which adds cost.

How Amboss handles payment gateways

Amboss Payments is not a custodial gateway. It is software that lets a business accept and send Bitcoin, USDT and USDC over the Lightning Network through one GraphQL API. Payments settle to the business's own wallet, and Amboss does not hold, receive or proxy the funds. Completed payments are final, so there are no card chargebacks. Refunds are separate payments that the business sends.

The integration flow on the payment providers page follows the steps above:

• Your backend requests a payment for the chosen wallet and amount.
• Your checkout shows the returned Lightning invoice as a QR code or link.
• Signed webhooks report completed, failed and expired payments. Verify the signature and deduplicate repeat deliveries before you update an order.
• A free sandbox is available to explore the API.

Pricing is tailored to payment volume and business requirements. The trade-off is that the merchant handles what happens after settlement, such as converting to fiat through a partner of its choice.

Businesses that keep balances after settlement can look at Amboss Rails, which earns yield from Lightning routing and liquidity leases without a change of custody. For regulatory questions, see crypto payment gateway regulations. For the wider market, see Amboss Payments.