Accept a B20 Payment - Base Documentation

B20 is an ERC-20 superset, so standard token integrations work unchanged. Use transferWithMemo when you also need an order or invoice reference emitted beside the payment for reconciliation.

Demo

Pay and read the memo

Read the token’s decimals, simulate the payment, then parse its Memo event from the confirmed receipt:

pay-with-memo.ts

import {
  type Address,
  hexToString,
  parseEventLogs,
  parseUnits,
  stringToHex,
} from 'viem';

const abi = [
  { type: 'function', name: 'decimals', stateMutability: 'view', inputs: [], outputs: [{ type: 'uint8' }] },
  { type: 'function', name: 'transferWithMemo', stateMutability: 'nonpayable', inputs: [
    { name: 'to', type: 'address' },
    { name: 'amount', type: 'uint256' },
    { name: 'memo', type: 'bytes32' },
  ], outputs: [{ type: 'bool' }] },
  { type: 'event', name: 'Memo', inputs: [
    { name: 'caller', type: 'address', indexed: true },
    { name: 'memo', type: 'bytes32', indexed: true },
  ] },
] as const;

export async function payWithMemo(token: Address, merchant: Address) {
const decimals = await publicClient.readContract({
  address: token, abi, functionName: 'decimals',
});
const payment = await publicClient.simulateContract({
  account: walletClient.account,
  address: token,
  abi,
  functionName: 'transferWithMemo',
  args: [merchant, parseUnits('25', decimals), stringToHex('order-8842', { size: 32 })],
});
const hash = await walletClient.writeContract(payment.request);
const receipt = await publicClient.waitForTransactionReceipt({ hash });
const [memo] = parseEventLogs({ abi, logs: receipt.logs, eventName: 'Memo' });

const orderId = hexToString(memo.args.memo, { size: 32 }).replace(/\0+$/, '');
console.log(orderId); // "order-8842"
}

A B20 transfer can revert when the issuer’s holder policy denies the sender or recipient, or when transfers are paused. Simulate the exact call and surface the decoded reason before asking the user to sign.

See also

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