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Overview

While Crossmint provides built-in wallet support, you can also integrate your own wallet solution using the payer prop. This is useful when:
  • You’re already using a wallet connection solution (like RainbowKit, Web3Modal, or ConnectKit)
  • You want to customize the transaction signing flow
  • You need to support specific wallets or chains

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Quick Integration

Here’s a simple example using wagmi and viem: 
import { CrossmintEmbeddedCheckout } from "@crossmint/client-sdk-react-ui";
import { useAccount, useWalletClient } from "wagmi";
import { Hex, parseTransaction } from "viem";

function Checkout() {
    const { data: walletClient } = useWalletClient();
    const { address } = useAccount();

    // Map of supported chains to their IDs
    const chainIds = {
        "base-sepolia": 84532,
        "polygon-amoy": 80002,
    } as const;

    if (!address || !walletClient) {
        return <p>Connect your wallet to continue</p>;
    }

    return (
        <CrossmintEmbeddedCheckout
            lineItems={{
                collectionLocator: "crossmint:__YOUR_COLLECTION_ID__",
                callData: {
                    totalPrice: "0.001",
                    quantity: 1,
                },
            }}
            payment={{
                crypto: {
                    // Enable crypto payment, this example only uses Crypto
                    enabled: true,
                    payer: {
                        address,
                        initialChain: "base-sepolia",
                        supportedChains: ["base-sepolia", "polygon-amoy"],
                        handleChainSwitch: async (chain) => {
                            await walletClient.switchChain({
                                id: chainIds[chain],
                            });
                        },
                        handleSignAndSendTransaction: async (serializedTx) => {
                            try {
                                const tx = parseTransaction(serializedTx as Hex);
                                const hash = await walletClient.sendTransaction({
                                    to: tx.to,
                                    value: tx.value,
                                    data: tx.data ?? "0x",
                                    gas: tx.gas,
                                    chainId: tx.chainId,
                                });

                                return { success: true, txId: hash };
                            } catch (error) {
                                return {
                                    success: false,
                                    errorMessage: error instanceof Error ? error.message : "Transaction failed",
                                };
                            }
                        },
                    },
                },
                // Disable fiat payment
                fiat: { enabled: false },
            }}
        />
    );
}
When the user clicks the hosted checkout button, our SDK will first call handleChainSwitch to ensure the correct network is set, then handleSignAndSendTransaction to complete the purchase.

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Payer Configuration

The payer prop accepts the following configuration:
PropertyTypeDescription
addressstringThe wallet address of the payer
initialChainPayerSupportedBlockchainsThe initial blockchain (e.g. “polygon”, “ethereum”, “base-sepolia”)
supportedChainsPayerSupportedBlockchains[]Optional list of supported chains. Defaults to initialChain if not specified
handleChainSwitch(chain: PayerSupportedBlockchains) => Promise<void>Function to handle chain switching
handleSignAndSendTransaction(serializedTx: string) => Promise<TransactionResponse>Function to handle transaction signing and sending, where TransactionResponse is either { success: true, txId: string } or { success: false, errorMessage: string }
You can integrate Crossmint with popular Web3 solutions:

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RainbowKit

import { useConnectModal } from "@rainbow-me/rainbowkit";

// Similar implementation as above, but using RainbowKit's hooks

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Web3Modal

import { useWeb3Modal } from "@web3modal/react";

// Similar implementation as above, but using Web3Modal's hooks

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Best Practices

  1. Error Handling: Always return clear error messages in handleSignAndSendTransaction
  2. Chain Support: Be explicit about supported chains to avoid runtime errors
  3. User Experience: Show loading states during chain switches and transactions
  4. Wallet Connection: Ensure wallet is connected before showing checkout