5 Minute Crypto Onramp Quickstart

In this guide, you will learn how to:

Install the React SDK
Create an Onramp order for your authenticated users
Use the embedded checkout component to handle KYC, payment, and delivery

Before you start

Set up your project and get an API key.

Onramp Embedded Quickstart

See a full working example.

You can test the Onramp self-serve in staging. To enable it in production, contact sales.

1. Prerequisites

Install the SDK

Install the Crossmint client SDK:

npm i @crossmint/client-sdk-react-ui

yarn add @crossmint/client-sdk-react-ui

pnpm add @crossmint/client-sdk-react-ui

bun add @crossmint/client-sdk-react-ui

Create API keys

Create a server-side API key with the orders.create and orders.read scopes enabled.
Create a client-side API key for the embedded checkout component.

Add environment variables

Add environment variables to your .env.local:

.env.local

NEXT_PUBLIC_CROSSMINT_CLIENT_SIDE_API_KEY="_YOUR_CLIENT_API_KEY_"
CROSSMINT_SERVER_SIDE_API_KEY="_YOUR_SERVER_API_KEY_"

Onramp to Crossmint Wallets
Onramp to External Wallets

2. Create the Server Action

Create a server action that will create orders via the Crossmint API:

app/actions/createOrder.ts

"use server";

const USDC_TOKEN_LOCATORS = {
    solanaDevnet: "solana:4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU",
    baseSepolia: "base-sepolia:0x036CbD53842c5426634e7929541eC2318f3dCF7e",
    stellarTestnet: "stellar:CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA",
};

interface CreateOrderParams {
    walletAddress: string;
    receiptEmail: string;
    amount: string;
    chain: "solanaDevnet" | "baseSepolia" | "stellarTestnet";
}

export async function createOrder({ walletAddress, receiptEmail, amount, chain }: CreateOrderParams) {
    const serverApiKey = process.env.CROSSMINT_SERVER_SIDE_API_KEY;
    if (serverApiKey == null) {
        throw new Error("CROSSMINT_SERVER_SIDE_API_KEY is not set");
    }

    const response = await fetch("https://staging.crossmint.com/api/2022-06-09/orders", {
        method: "POST",
        headers: {
            "Content-Type": "application/json",
            "x-api-key": serverApiKey,
        },
        body: JSON.stringify({
            lineItems: [
                {
                    tokenLocator: USDC_TOKEN_LOCATORS[chain],
                    executionParameters: {
                        mode: "exact-in",
                        amount,
                    },
                },
            ],
            payment: {
                method: "card",
                receiptEmail,
            },
            recipient: {
                walletAddress,
            },
        }),
    });

    if (!response.ok) {
        const error = await response.json();
        throw new Error(error.message || "Failed to create order");
    }

    return response.json();
}

3. Build the Onramp Component

Create a client component that handles the order creation and displays the embedded checkout:

app/components/OnrampCheckout.tsx

"use client";

import { useState } from "react";
import { CrossmintProvider, CrossmintEmbeddedCheckout } from "@crossmint/client-sdk-react-ui";
import { createOrder } from "../actions/createOrder";

const CLIENT_API_KEY = process.env.NEXT_PUBLIC_CROSSMINT_CLIENT_SIDE_API_KEY || "";

// Destination wallets for testing transfers on each network
const TEST_WALLETS = {
    solanaDevnet: "<destination_wallet_address>",
    baseSepolia: "<destination_wallet_address>",
    stellarTestnet: "<destination_wallet_address>",
};

export default function OnrampCheckout() {
    const [order, setOrder] = useState<{ orderId: string; clientSecret: string } | null>(null);
    const [chain, setChain] = useState<"solanaDevnet" | "baseSepolia" | "stellarTestnet">("solanaDevnet");
    const [email, setEmail] = useState("user@example.com");
    const [wallet, setWallet] = useState(TEST_WALLETS.solanaDevnet);
    const [amount, setAmount] = useState("5");
    const [isLoading, setIsLoading] = useState(false);

    function handleChainChange(newChain: "solanaDevnet" | "baseSepolia" | "stellarTestnet") {
        setChain(newChain);
        setWallet(TEST_WALLETS[newChain]);
    }

    async function handleSubmit() {
        setIsLoading(true);
        try {
            const result = await createOrder({ walletAddress: wallet, receiptEmail: email, amount, chain });
            setOrder({ orderId: result.order.orderId, clientSecret: result.clientSecret });
        } catch (error) {
            console.error("Failed to create order:", error);
        } finally {
            setIsLoading(false);
        }
    }

    if (order != null) {
        return (
            <CrossmintProvider apiKey={CLIENT_API_KEY}>
                <div className="max-w-[450px] w-full mx-auto p-6 rounded-xl bg-white">
                    <CrossmintEmbeddedCheckout
                        orderId={order.orderId}
                        clientSecret={order.clientSecret}
                        payment={{
                            receiptEmail: email,
                            crypto: { enabled: false },
                            fiat: { enabled: true },
                            defaultMethod: "fiat",
                        }}
                    />
                </div>
            </CrossmintProvider>
        );
    }

    return (
        <div className="max-w-md mx-auto p-8 rounded-xl border border-gray-300 bg-white shadow-sm space-y-6">
            <h2 className="text-2xl font-semibold text-gray-900">Buy USDC</h2>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Network</label>
                <div className="grid grid-cols-3 gap-2">
                    <button
                        type="button"
                        onClick={() => handleChainChange("solanaDevnet")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "solanaDevnet"
                                ? "bg-green-600 text-white border-green-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Solana Devnet
                    </button>
                    <button
                        type="button"
                        onClick={() => handleChainChange("baseSepolia")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "baseSepolia"
                                ? "bg-blue-600 text-white border-blue-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Base Sepolia
                    </button>
                    <button
                        type="button"
                        onClick={() => handleChainChange("stellarTestnet")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "stellarTestnet"
                                ? "bg-purple-600 text-white border-purple-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Stellar Testnet
                    </button>
                </div>
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Email</label>
                <input
                    type="email"
                    value={email}
                    onChange={(e) => setEmail(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm"
                />
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Recipient Wallet</label>
                <input
                    type="text"
                    value={wallet}
                    onChange={(e) => setWallet(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm font-mono"
                />
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Amount (USD)</label>
                <input
                    type="number"
                    value={amount}
                    onChange={(e) => setAmount(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm"
                />
            </div>

            <button
                onClick={handleSubmit}
                disabled={isLoading || !email || !wallet}
                className="w-full py-3 rounded-lg bg-black text-white font-medium hover:bg-gray-800 disabled:opacity-50 transition-colors"
            >
                {isLoading ? "Creating Order..." : "Continue to Checkout"}
            </button>
        </div>
    );
}

4. Add the Component to Your Page

Import and render the OnrampCheckout component in your page:

app/page.tsx

import OnrampCheckout from "./components/OnrampCheckout";

export default function Home() {
    return (
        <main className="min-h-screen flex items-center justify-center">
            <OnrampCheckout />
        </main>
    );
}

That’s it! When users fill in their details and click “Continue to Checkout”, the server action creates an order and the embedded checkout component handles KYC, payment, and delivery automatically.

Use this tab if you want to onramp to external wallets — externally owned accounts (EOAs) or smart wallets not created by Crossmint.External wallet onramp requires two additional steps compared to Crossmint wallets: linking the wallet to a Crossmint user, and handling ownership verification when transaction thresholds are exceeded.

2. Link External Wallet

Before creating an onramp order to an external wallet, you must link the wallet to a Crossmint user using the Link External Wallet API.Create a server action to handle the wallet linking:

app/actions/linkWallet.ts

"use server";

interface LinkWalletParams {
    userEmail: string;
    walletAddress: string;
    chain: string;
    proof?: string;
}

export async function linkWallet({ userEmail, walletAddress, chain, proof }: LinkWalletParams) {
    const serverApiKey = process.env.CROSSMINT_SERVER_SIDE_API_KEY;
    if (serverApiKey == null) {
        throw new Error("CROSSMINT_SERVER_SIDE_API_KEY is not set");
    }

    const userLocator = `email:${userEmail}`;

    const body: Record<string, string> = { chain };
    if (proof) {
        body.proof = proof;
    }

    const response = await fetch(
        `https://staging.crossmint.com/api/2025-06-09/users/${userLocator}/linked-wallets/${walletAddress}`,
        {
            method: "PUT",
            headers: {
                "Content-Type": "application/json",
                "x-api-key": serverApiKey,
            },
            body: JSON.stringify(body),
        }
    );

    if (!response.ok) {
        const error = await response.json();
        throw new Error(error.message || "Failed to link wallet");
    }

    return response.json();
}

The proof field is optional:

If you omit it, the wallet is linked without proving ownership yet. The API responds with a verificationChallenge that you can use later to verify ownership.
If you pass it, you prove ownership of the wallet in the same request.

3. Create the Server Action

Create a server action that will create orders via the Crossmint API:

app/actions/createOrder.ts

"use server";

const USDC_TOKEN_LOCATORS = {
    solanaDevnet: "solana:4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU",
    baseSepolia: "base-sepolia:0x036CbD53842c5426634e7929541eC2318f3dCF7e",
    stellarTestnet: "stellar:CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA",
};

interface CreateOrderParams {
    walletAddress: string;
    receiptEmail: string;
    amount: string;
    chain: "solanaDevnet" | "baseSepolia" | "stellarTestnet";
}

export async function createOrder({ walletAddress, receiptEmail, amount, chain }: CreateOrderParams) {
    const serverApiKey = process.env.CROSSMINT_SERVER_SIDE_API_KEY;
    if (serverApiKey == null) {
        throw new Error("CROSSMINT_SERVER_SIDE_API_KEY is not set");
    }

    const response = await fetch("https://staging.crossmint.com/api/2022-06-09/orders", {
        method: "POST",
        headers: {
            "Content-Type": "application/json",
            "x-api-key": serverApiKey,
        },
        body: JSON.stringify({
            lineItems: [
                {
                    tokenLocator: USDC_TOKEN_LOCATORS[chain],
                    executionParameters: {
                        mode: "exact-in",
                        amount,
                    },
                },
            ],
            payment: {
                method: "card",
                receiptEmail,
            },
            recipient: {
                walletAddress,
            },
        }),
    });

    if (!response.ok) {
        const error = await response.json();
        throw new Error(error.message || "Failed to create order");
    }

    return response.json();
}

Ownership Verification

Depending on the transaction value and the user’s past activity, the order may or may not require wallet ownership verification:

Below threshold: If the transaction value is below $1,000 and the user’s past 30-day onramp transaction volume is below $1,000, ownership verification is not required. The order proceeds directly to the KYC/payment phase.
Above threshold: If either threshold is surpassed, the order status will be requires-recipient-verification and the user must sign a message to prove wallet ownership.

When ownership verification is required, the order response includes a preparation.message field that the user must sign:

{
    "payment": {
        "status": "requires-recipient-verification",
        "preparation": {
            "message": "crossmint.com wants you to sign in with your blockchain account:\n0x1234...5678\n\n..."
        }
    }
}

4. Handle Wallet Verification

If the order requires ownership verification, have the user sign the preparation.message with the recipient wallet. See Proof of Ownership for how all wallets, including EOAs and smart contract wallets, use the same verification flow.

import { Wallet } from "ethers";

const wallet = new Wallet("YOUR_PRIVATE_KEY");
const message = order.payment.preparation.message;
const signature = await wallet.signMessage(message);

import nacl from "tweetnacl";
import { decodeUTF8 } from "tweetnacl-util";
import { encode as base64Encode } from "@stablelib/base64";

const message = order.payment.preparation.message;
const messageBytes = decodeUTF8(message);
const signatureBytes = nacl.sign.detached(messageBytes, keypair.secretKey);
const signature = base64Encode(signatureBytes);

Once signed, submit the signature using the same Link External Wallet API by calling the linkWallet server action with the proof parameter set to the signature. Once ownership is verified, the order proceeds to the next phase (requires-kyc or awaiting-payment).

5. Build the Onramp Component

Create a client component that handles wallet linking, order creation, and displays the embedded checkout:

app/components/OnrampCheckout.tsx

"use client";

import { useState } from "react";
import { CrossmintProvider, CrossmintEmbeddedCheckout } from "@crossmint/client-sdk-react-ui";
import { createOrder } from "../actions/createOrder";
import { linkWallet } from "../actions/linkWallet";

const CLIENT_API_KEY = process.env.NEXT_PUBLIC_CROSSMINT_CLIENT_SIDE_API_KEY || "";

// Destination wallets for testing transfers on each network
const TEST_WALLETS = {
    solanaDevnet: "YOUR_DESTINATION_WALLET_ADDRESS",
    baseSepolia: "YOUR_DESTINATION_WALLET_ADDRESS",
    stellarTestnet: "YOUR_DESTINATION_WALLET_ADDRESS",
};

const CHAIN_MAP = {
    solanaDevnet: "solana",
    baseSepolia: "base-sepolia",
    stellarTestnet: "stellar",
};

export default function OnrampCheckout() {
    const [order, setOrder] = useState<{ orderId: string; clientSecret: string } | null>(null);
    const [chain, setChain] = useState<"solanaDevnet" | "baseSepolia" | "stellarTestnet">("solanaDevnet");
    const [email, setEmail] = useState("user@example.com");
    const [wallet, setWallet] = useState(TEST_WALLETS.solanaDevnet);
    const [amount, setAmount] = useState("5");
    const [isLoading, setIsLoading] = useState(false);

    function handleChainChange(newChain: "solanaDevnet" | "baseSepolia" | "stellarTestnet") {
        setChain(newChain);
        setWallet(TEST_WALLETS[newChain]);
    }

    async function handleSubmit() {
        setIsLoading(true);
        try {
            // Step 1: Link the external wallet to the Crossmint user
            await linkWallet({
                userEmail: email,
                walletAddress: wallet,
                chain: CHAIN_MAP[chain],
            });

            // Step 2: Create the onramp order
            const result = await createOrder({ walletAddress: wallet, receiptEmail: email, amount, chain });
            setOrder({ orderId: result.order.orderId, clientSecret: result.clientSecret });
        } catch (error) {
            console.error("Failed to create order:", error);
        } finally {
            setIsLoading(false);
        }
    }

    if (order != null) {
        return (
            <CrossmintProvider apiKey={CLIENT_API_KEY}>
                <div className="max-w-[450px] w-full mx-auto p-6 rounded-xl bg-white">
                    <CrossmintEmbeddedCheckout
                        orderId={order.orderId}
                        clientSecret={order.clientSecret}
                        payment={{
                            receiptEmail: email,
                            crypto: { enabled: false },
                            fiat: { enabled: true },
                            defaultMethod: "fiat",
                        }}
                    />
                </div>
            </CrossmintProvider>
        );
    }

    return (
        <div className="max-w-md mx-auto p-8 rounded-xl border border-gray-300 bg-white shadow-sm space-y-6">
            <h2 className="text-2xl font-semibold text-gray-900">Buy USDC</h2>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Network</label>
                <div className="grid grid-cols-3 gap-2">
                    <button
                        type="button"
                        onClick={() => handleChainChange("solanaDevnet")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "solanaDevnet"
                                ? "bg-green-600 text-white border-green-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Solana Devnet
                    </button>
                    <button
                        type="button"
                        onClick={() => handleChainChange("baseSepolia")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "baseSepolia"
                                ? "bg-blue-600 text-white border-blue-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Base Sepolia
                    </button>
                    <button
                        type="button"
                        onClick={() => handleChainChange("stellarTestnet")}
                        className={`p-3 rounded-lg border text-sm font-medium transition-colors ${
                            chain === "stellarTestnet"
                                ? "bg-purple-600 text-white border-purple-600"
                                : "bg-white text-gray-900 border-gray-300 hover:bg-gray-100"
                        }`}
                    >
                        Stellar Testnet
                    </button>
                </div>
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Email</label>
                <input
                    type="email"
                    value={email}
                    onChange={(e) => setEmail(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm"
                />
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Recipient Wallet</label>
                <input
                    type="text"
                    value={wallet}
                    onChange={(e) => setWallet(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm font-mono"
                />
            </div>

            <div className="space-y-2">
                <label className="text-sm font-medium text-gray-900">Amount (USD)</label>
                <input
                    type="number"
                    value={amount}
                    onChange={(e) => setAmount(e.target.value)}
                    className="w-full px-3 py-2 rounded-lg border border-gray-300 bg-white text-gray-900 text-sm"
                />
            </div>

            <button
                onClick={handleSubmit}
                disabled={isLoading || !email || !wallet}
                className="w-full py-3 rounded-lg bg-black text-white font-medium hover:bg-gray-800 disabled:opacity-50 transition-colors"
            >
                {isLoading ? "Creating Order..." : "Continue to Checkout"}
            </button>
        </div>
    );
}

6. Add the Component to Your Page

Import and render the OnrampCheckout component in your page:

app/page.tsx

import OnrampCheckout from "./components/OnrampCheckout";

export default function Home() {
    return (
        <main className="min-h-screen flex items-center justify-center">
            <OnrampCheckout />
        </main>
    );
}

That is it! When users fill in their details and click “Continue to Checkout”, the app links the external wallet, creates an order, and the embedded checkout component handles KYC, payment, and delivery automatically.

Testing: Use the test credit card number 4242 4242 4242 4242 with any future expiration date and any 3-digit CVC.

Transaction Completion

Upon successful payment:

KYC Verification

The embedded checkout component handles all the complexity of KYC verification automatically.

Token Delivery

The purchased tokens (minus fees) are sent directly to the user's wallet.

Receipt Sent

User receives an email receipt from hello@crossmint.io.

Next Steps

Explore our Payment Methods Guide to learn about different payment options
Check out our Production Launch Guide for going live

Introduction

Quickstarts ⚡

Concepts

Guides

API Reference

React

Before you start

Onramp Embedded Quickstart

1. Prerequisites

2. Create the Server Action

3. Build the Onramp Component

4. Add the Component to Your Page

2. Link External Wallet

3. Create the Server Action

Ownership Verification

4. Handle Wallet Verification

5. Build the Onramp Component

6. Add the Component to Your Page

Transaction Completion

Next Steps

Before you start

Onramp Embedded Quickstart

​1. Prerequisites

​2. Create the Server Action

​3. Build the Onramp Component

​4. Add the Component to Your Page

​2. Link External Wallet

​3. Create the Server Action

​Ownership Verification

​4. Handle Wallet Verification

​5. Build the Onramp Component

​6. Add the Component to Your Page

​Transaction Completion

​Next Steps

1. Prerequisites

2. Create the Server Action

3. Build the Onramp Component

4. Add the Component to Your Page

2. Link External Wallet

3. Create the Server Action

Ownership Verification

4. Handle Wallet Verification

5. Build the Onramp Component

6. Add the Component to Your Page

Transaction Completion

Next Steps