How to accept crypto with a crypto payment API

A developer's guide to wiring crypto payments into your product with a crypto payment API, from your first API key to fiat settlement.

August 4, 2026 · 8 min read

You can accept crypto with a hosted checkout, a payment link, or a plugin. A crypto payment API is the option you reach for when payments need to live inside your own product, on your own screens, triggered by your own code.

This guide is written for the developer (or coding agent) who has to build that integration. It walks through what a crypto payment API actually does, the exact calls involved in a pay-in, how webhooks confirm a payment, and how settlement to fiat works so your finance team is not left holding volatile coins.

A crypto payment API is a set of endpoints your application calls to accept crypto and to send them. It gives your product programmatic control over the parts a hosted page would otherwise handle for you: creating a payment, showing the customer where to send funds, tracking confirmation on-chain, and settling the result to your bank account.

The EukaPay crypto payment gateway exposes this through a REST API. You authenticate with a key, create a charge for a specific amount, and receive back the addresses and status your product needs to complete the payment.

A pay-in is money coming in. Your application creates a charge, the customer sends crypto to the address returned by the API, and the API reports the payment as confirmed once the network verifies it. EukaPay supports most major cryptocurrencies like BTC, ETH, LTC, SOL, USDC, USDT, so your checkout can accept the coins your customers actually hold.

A payout is money going out. The same crypto payment API sends crypto to contractors, affiliates, or vendors programmatically, which is how businesses run crypto payouts at scale without sending each transfer manually.

Here is the sequence for a single pay-in with the EukaPay crypto payment gateway API. The full reference lives in the EukaPay developer documentation.

Step 1 - Get your API key.

Every merchant goes through onboarding and a business review before going live. A sandbox environment is available so your developer (or coding agent) can build and test against the crypto payment API during the review period. You generate a key in the dashboard and pass it in the request header.

Step 2 - Create a charge.

Your application sends a request to the charges endpoint with the amount, the fiat currency you are pricing in, and an order reference. The API returns a charge object that includes a payment address and a status field set to a pending state.

Step 3 - Present the payment to the customer.

Your product shows the customer the amount and the address, or renders the returned checkout details on your own screens. The customer sends crypto from their wallet.

Step 4 - Listen for webhooks.

Rather than polling, your application registers a webhook URL. When the payment is detected and then confirmed on-chain, the crypto payment API sends your endpoint an event with the updated status. Your system reads the event, verifies its signature, and marks the order as paid.

Step 5 - Settle to fiat.

The confirmed payment is converted at a locked exchange rate to remove all crypto volatility, and settled in USD, EUR, GBP, CAD to your bank account. Your finance team receives fiat, not coins whose value can move between checkout and payout.

A crypto payment API is not always the right first step. The table below is the picking heuristic.

Businesses often combine both. A company can launch on a hosted checkout or payment links first, then move high-volume or embedded flows onto the crypto payment API once product requirements are clear.

Whichever integration path you choose, the same infrastructure runs beneath it: instant crypto-to-fiat conversion at a locked exchange rate to remove all crypto volatility, protection against chargebacks, support for a wide range of cryptocurrencies, and settlement in USD, EUR, GBP, CAD to your bank account.

The crypto payment API is the programmatic entry point to that infrastructure. The choice between the API and a hosted checkout is a question of how much control your product needs, not a question of which one is better.

Create an account to generate your keys and start building in the sandbox while your business review is underway, and read the

EukaPay developer documentation

for the full endpoint reference. You can review the

crypto payment API product page

for capabilities, or the

crypto payment gateway overview

for how pay-ins settle to fiat.

What is a crypto payment API?

It is a set of endpoints your application calls to accept crypto as pay-ins and to send crypto payouts, with confirmation and fiat settlement handled by EukaPay.

Which cryptocurrencies can I accept through the API?

EukaPay supports most major cryptocurrencies like BTC, ETH, LTC, SOL, USDC, USDT.

How do I get notified when a payment is confirmed?

You register a webhook URL. The crypto payment API sends your endpoint an event when a payment is detected and again when it is confirmed on-chain.

Can I test the API before going live?

Yes. A sandbox environment is available so you can build and test during your onboarding and business review. EukaPay does not offer instant registration.

How does settlement work?

Confirmed payments are converted at a locked exchange rate to remove all crypto volatility and settled in USD, EUR, GBP, CAD to your bank account.

Do I need to build a checkout to use the API?

No. You can render payment details on your own screens, or start with a hosted checkout and move to the crypto payment API later.

Can the same API send payouts?

Yes. The same crypto payment API sends crypto to recipients, which is how businesses automate crypto payouts.