Gasless Trading

Gasless execution is available for Trade (swap/bridge) only — the SDK has no gasless flow for Zap. Instead of sending a transaction, the user signs an EIP-712 permit; DZap’s relay submits it and pays gas on their behalf.

The underlying signing utility (signGaslessDzapUserIntent) is internal and not exported from @dzapio/sdk. Use the high-level tradeGasless() method below — it handles building, signing, and submission for you.

`tradeGasless()`

public async tradeGasless(params: {
  request: TradeBuildTxnRequest;
  signer: Signer | WalletClient;
  txnData?: GaslessTradeBuildTxnResponse; // optional pre-built data, skips the build step
  txnStatusCallback?: (status: TxnStatus) => void;
}): Promise<DZapTransactionResponse>

Set gasless: true on the request. tradeGasless() will:

Build the transaction via POST /v1/buildTx (unless you pass pre-built txnData) — this returns a GaslessTradeBuildTxnResponse with a typed-data payload to sign.
Prompt the signer for an EIP-712 signature over that payload (EIP-2612 permit, or a batch Permit2 signature if request.hasPermit2ApprovalForAllTokens is set).
Submit the signed permit to POST /v1/gasless/executeTx for the relay to execute.
Optionally call txnStatusCallback with TxnStatus.waitingForExecution once the signature is submitted.

import { DZapClient, TxnStatus } from '@dzapio/sdk';
import type { TradeBuildTxnRequest } from '@dzapio/sdk';

const dzap = DZapClient.getInstance();

const request: TradeBuildTxnRequest = {
  fromChain: 1,
  sender: userAccount,
  refundee: userAccount,
  gasless: true,
  data: [
    {
      amount: '1000000',
      srcToken: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // USDC
      destToken: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2', // WETH
      srcDecimals: 6,
      destDecimals: 18,
      toChain: 42161,
      protocol: 'across', // from getTradeQuotes()
      recipient: userAccount,
      slippage: 1,
    },
  ],
};

const result = await dzap.tradeGasless({
  request,
  signer: walletClient,
  txnStatusCallback: (status) => console.log('status:', status),
});

if (result.status === TxnStatus.success) {
  console.log('Submitted:', result.txnHash);
} else {
  console.error(result.errorMsg);
}

Why the hashes matter

The build response’s typed-data payload commits to executorFeesHash and (for swaps) swapDataHash — the relay can’t inflate fees or substitute a worse route after you sign, because those values are hashed into the signed message. If either is tampered with, on-chain verification reverts.

Deadline

The signed permit carries a deadline; past it, the relay can no longer submit it and you’ll need to rebuild and re-sign. For the non-gasless flow, see Execute Trade. For Zap execution (always requires gas from the user — there is no zap gasless mode), see Execute Zap.

​tradeGasless()

​Why the hashes matter

​Deadline

`tradeGasless()`

Why the hashes matter

Deadline