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Introduction

Once a signer is authorized, your agent can drive the wallet like any EOA: send stablecoins, swap, bridge, or call an arbitrary contract. All operations go through the same wallet handle — the only thing that changes is which signer is active. Policies attached to the server signer (spend caps, allowed contracts) are enforced on every transaction, so the agent can only sign what the user delegated.

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Prerequisites

  • A user wallet with an authorized server signer. See Authorize the Agent if you have not done this yet.
  • The walletAddress of the user’s wallet.
  • A Crossmint server-side API key and the CROSSMINT_SIGNER_SECRET for the authorized signer.

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Activate the Server Signer

Before any server-side signing, activate the authorized server signer. Every subsequent call on that wallet handle is signed in-process with no user prompt. 
import { createCrossmint, CrossmintWallets } from "@crossmint/wallets-sdk";

const crossmint = createCrossmint({
    apiKey: process.env.CROSSMINT_SERVER_SIDE_API_KEY,
});
const wallets = CrossmintWallets.from(crossmint);

const wallet = await wallets.getWallet(walletAddress, { chain: "base-sepolia" });

await wallet.useSigner({
    type: "server",
    secret: process.env.CROSSMINT_SIGNER_SECRET,
});

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Send Stablecoins

The canonical agent action: transfer stablecoins to a recipient. Wrap it in a server action so the secret stays on the backend. 
"use server";

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

export async function sendUsdxmFromServer({
    walletAddress,
    recipient,
    amount,
}: {
    walletAddress: string;
    recipient: string;
    amount: string;
}) {
    const crossmint = createCrossmint({
        apiKey: process.env.CROSSMINT_SERVER_SIDE_API_KEY,
    });
    const wallets = CrossmintWallets.from(crossmint);
    const wallet = await wallets.getWallet(walletAddress, { chain: "base-sepolia" });

    await wallet.useSigner({
        type: "server",
        secret: process.env.CROSSMINT_SIGNER_SECRET,
    });

    const tx = await wallet.send(recipient, "usdxm", amount);
    return { hash: tx.hash, explorerLink: tx.explorerLink };
}
wallet.send(recipient, symbol, amount) accepts any token symbol the chain supports (usdc, usdt, usdxm on staging, native gas tokens). The transaction is sponsored by default — the user does not need to hold ETH for gas. See Transfer Tokens for the full symbol list and per-chain behavior.

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Read Balances

const balances = await wallet.balances(["usdxm", "eth"]);
const usdxm = balances.tokens.find((t) => t.symbol === "usdxm");
balances() returns native balance and token balances in one call. Pass an explicit array to include non-default symbols. For richer patterns (historical, multi-chain aggregation), see Check Balances.

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Fund a Staging Wallet

On supported staging chains, you can mint test stablecoins directly into the wallet — no faucet round-trip. 
await wallet.stagingFund(5); // 5 USDXM
This is staging-only and exists to unblock local development. For production funding flows, see Onramp & Add Funds. For EVM-native testnet tokens, see Get Staging Tokens.

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Call Any Contract

The wallet exposes a generic transaction path for anything that is not a first-class helper — swaps, bridges, DeFi, NFT mints, custom protocols. The exact call shape differs per chain; follow the reference for the chain you are targeting:
ChainReference
EVMSend Transaction (EVM)
SolanaSend Transaction (Solana)
StellarSend Transaction (Stellar)

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Common Gotchas

Activating a signer applies only to the wallet handle you call it on. If you load a fresh wallet via getWallet, you must call useSigner again before signing.

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Next Steps

x402 Payment Flow

Pay HTTP-402-gated endpoints automatically using the authorized wallet.

Wallet Guides

Full reference for signers, transactions, webhooks, and error handling.