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Crossmint’s embedded wallets allow you to create and manage blockchain wallets for your users seamlessly. Users can interact with blockchain applications without needing to understand seed phrases, private keys, or wallet extensions.

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Overview

Embedded wallets provide:
  • Email/Social login - Users sign in with familiar methods
  • Multi-chain support - One wallet across EVM and Solana chains
  • Custodial & non-custodial options - Choose the right model for your use case
  • No seed phrases - Better UX for non-crypto users

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Installation

npm install @crossmint/wallets-sdk @crossmint/common-sdk-base

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Quick Start

1

Initialize the Crossmint SDK

import { createCrossmint } from "@crossmint/common-sdk-base";
import { CrossmintWallets } from "@crossmint/wallets-sdk";

const crossmint = createCrossmint({
  apiKey: "YOUR_API_KEY",
});

const wallets = CrossmintWallets.from(crossmint);
2

Create or get a wallet

// Get or create a wallet for the authenticated user
const wallet = await wallets.getOrCreateWallet({
  chain: "ethereum-sepolia",
  signer: {
    type: "api-key",
    locator: "user-id-123", // Your user's identifier
  },
});

console.log("Wallet address:", wallet.address);
console.log("Chain:", wallet.chain);
3

Check the wallet balance

const balances = await wallet.getBalance();

console.log("Native balance:", balances.native.raw);
console.log("Token balances:", balances.tokens);

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Creating Wallets

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Client-Side Creation

Create wallets in your frontend application: 
const wallet = await wallets.getOrCreateWallet({
  chain: "ethereum-sepolia",
  signer: {
    type: "api-key",
    locator: "[email protected]",
  },
});

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Server-Side Creation

For more control, create wallets from your backend: 
// Backend code with server API key
const wallet = await wallets.createWallet({
  chain: "polygon-amoy",
  signer: {
    type: "api-key",
    locator: `user:${userId}`,
  },
});

// Return wallet address to frontend
return { address: wallet.address };
Use getOrCreateWallet() to ensure you don’t create duplicate wallets for the same user.

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Multi-Chain Wallets

Create wallets on different chains for the same user: 
// EVM chains
const ethWallet = await wallets.getOrCreateWallet({
  chain: "ethereum-sepolia",
  signer: { type: "api-key", locator: "user-123" },
});

const polygonWallet = await wallets.getOrCreateWallet({
  chain: "polygon-amoy",
  signer: { type: "api-key", locator: "user-123" },
});

// Solana
const solanaWallet = await wallets.getOrCreateWallet({
  chain: "solana-devnet",
  signer: { type: "api-key", locator: "user-123" },
});

EVM Chains

Ethereum, Polygon, Base, Arbitrum, Optimism, and more

Solana

Solana mainnet and devnet support

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Sending Transactions

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EVM Transactions

import { EVMWallet } from "@crossmint/wallets-sdk";

const evmWallet = EVMWallet.from(wallet);

const result = await evmWallet.sendTransaction({
  to: "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
  value: "0.01", // in ETH
});

console.log("Transaction hash:", result.hash);
console.log("Explorer link:", result.explorerLink);

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Solana Transactions

import { SolanaWallet } from "@crossmint/wallets-sdk";
import { Transaction, SystemProgram, PublicKey } from "@solana/web3.js";

const solanaWallet = SolanaWallet.from(wallet);

// Create your transaction
const transaction = new Transaction().add(
  SystemProgram.transfer({
    fromPubkey: new PublicKey(solanaWallet.address),
    toPubkey: new PublicKey("recipient-address"),
    lamports: 1000000, // 0.001 SOL
  })
);

// Serialize and send
const serialized = transaction.serialize().toString("base64");
const result = await solanaWallet.sendTransaction({
  serializedTransaction: serialized,
});

console.log("Transaction hash:", result.hash);

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Checking Balances

Retrieve native and token balances: 
const balances = await wallet.getBalance();

// Native currency (ETH, SOL, etc.)
console.log("Native balance:", {
  raw: balances.native.raw,
  formatted: balances.native.formatted,
  symbol: balances.native.symbol,
});

// Token balances
for (const token of balances.tokens) {
  console.log(`${token.symbol}: ${token.formatted}`);
}

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Signing Messages

Sign arbitrary messages for authentication or verification: 
// EVM message signing
const evmWallet = EVMWallet.from(wallet);
const signature = await evmWallet.signMessage({
  message: "Sign this message to authenticate",
});

console.log("Signature:", signature.signature);

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Transaction History

Retrieve transaction history for a wallet: 
const transactions = await wallet.getTransactions();

for (const tx of transactions) {
  console.log("Transaction ID:", tx.id);
  console.log("Status:", tx.status);
  console.log("Hash:", tx.onChain?.txId);
  console.log("Explorer:", tx.onChain?.explorerLink);
}

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Delegated Signers

Allow third parties to sign transactions on behalf of a wallet: 
const result = await wallet.addDelegatedSigner({
  signer: {
    type: "api-key",
    locator: "backend-service",
  },
});

console.log("Delegated signer added:", result.signer);
Delegated signers have full control over the wallet. Only add trusted parties as delegated signers.

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Best Practices

1

Use meaningful locators

Use consistent, meaningful identifiers for your users:
locator: `user:${userId}` // Good
locator: `${randomString}` // Bad
2

Handle errors gracefully

try {
  const wallet = await wallets.getOrCreateWallet({
    chain: "ethereum-sepolia",
    signer: { type: "api-key", locator: userId },
  });
} catch (error) {
  console.error("Failed to create wallet:", error);
  // Show user-friendly error message
}
3

Cache wallet addresses

Store wallet addresses in your database to avoid repeated API calls:
// First time
const wallet = await wallets.getOrCreateWallet({...});
await db.users.update(userId, { walletAddress: wallet.address });

// Later
const address = await db.users.get(userId).walletAddress;

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React Integration

For React applications, use the UI SDK: 
npm install @crossmint/client-sdk-react-ui

import { CrossmintProvider, useWallet } from "@crossmint/client-sdk-react-ui";

function WalletInfo() {
  const { wallet, isLoading } = useWallet();

  if (isLoading) return <div>Loading wallet...</div>;

  return (
    <div>
      <p>Address: {wallet?.address}</p>
      <p>Chain: {wallet?.chain}</p>
    </div>
  );
}

function App() {
  return (
    <CrossmintProvider apiKey="YOUR_API_KEY">
      <WalletInfo />
    </CrossmintProvider>
  );
}

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Next Steps

Custom Transactions

Build and send custom blockchain transactions

Multi-Chain Support

Work with multiple blockchain networks

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