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Swap tokens without users needing ETH or native tokens for gas. Biconomy handles gas abstraction—users can pay fees in the token they’re swapping, or you can sponsor gas entirely.

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How It Works

1

User Initiates Swap

User selects tokens and amount to swap
2

API Finds Best Route

Biconomy finds optimal route across DEXs and bridges
3

User Signs Once

Single signature approves the entire swap—no separate gas transaction
4

MEE Executes

Biconomy relayers execute and pay gas, deducting fee from swap or your sponsorship

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Quick Example

Swap 100 USDC on Base to USDT on Optimism—completely gasless: 
// 1. Request a quote
const quote = await fetch('https://api.biconomy.io/v1/quote', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    mode: 'smart-account',
    ownerAddress: '0xYourAddress',
    // No feeToken = sponsored (gasless)
    composeFlows: [{
      type: '/instructions/intent-simple',
      data: {
        srcChainId: 8453,           // Base
        dstChainId: 10,             // Optimism
        srcToken: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',  // USDC
        dstToken: '0x94b008aa00579c1307b0ef2c499ad98a8ce58e58',  // USDT
        amount: '100000000',        // 100 USDC (6 decimals)
        slippage: 0.01              // 1%
      }
    }]
  })
}).then(r => r.json());

// 2. Sign the payload
const signature = await wallet.signMessage({
  message: quote.payloadToSign[0].signablePayload.message
});

// 3. Execute
const result = await fetch('https://api.biconomy.io/v1/execute', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    ...quote,
    payloadToSign: [{ ...quote.payloadToSign[0], signature }]
  })
}).then(r => r.json());

console.log('Track at:', `https://meescan.biconomy.io/details/${result.supertxHash}`);

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Two Ways to Go Gasless

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Works with Any Wallet

Smart Accounts

Use mode: 'smart-account' for Nexus or ERC-4337 accounts. Native gas abstraction.

EOA Wallets

Use mode: 'eoa' for MetaMask, Rabby, etc. Requires fundingTokens parameter.

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EOA Example (MetaMask, Rabby, etc.)

const quote = await fetch('https://api.biconomy.io/v1/quote', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    mode: 'eoa',
    ownerAddress: userAddress,
    fundingTokens: [{
      tokenAddress: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',
      chainId: 8453,
      amount: '100000000'
    }],
    feeToken: {
      address: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',
      chainId: 8453
    },
    composeFlows: [{
      type: '/instructions/intent-simple',
      data: {
        srcChainId: 8453,
        dstChainId: 10,
        srcToken: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913',
        dstToken: '0x94b008aa00579c1307b0ef2c499ad98a8ce58e58',
        amount: '100000000',
        slippage: 0.01
      }
    }]
  })
}).then(r => r.json());

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Understanding the Response

The quote response tells you exactly what will happen: 
{
  "fee": {
    "amount": "50000",           // Fee in token units
    "token": "0x833589...",      // Fee token address
    "chainId": 8453
  },
  "returnedData": [{
    "outputAmount": "99500000",  // Expected output
    "minOutputAmount": "98505000", // After slippage
    "route": {
      "summary": "lifi[uniswap] => across",
      "estimatedTime": 120
    }
  }]
}
FieldWhat It Means
fee.amountHow much gas costs (in fee token units)
outputAmountExpected tokens user will receive
minOutputAmountMinimum after slippage protection
route.summaryWhich DEXs/bridges will be used

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Next Steps

Cross-Chain Swaps

Deep dive into multi-chain swap mechanics

Full API Tutorial

Learn the complete quote → sign → execute flow