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Cross-Chain Transfer Guide

This guide covers integrating the Zet Cross-Chain Transfer API to move tokens between different blockchains.

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Overview

Cross-chain transfers use the same underlying infrastructure as cross-chain swaps (LiFi aggregation) but are designed specifically for moving tokens from one chain to another, optionally converting to a different token on the destination chain. 
Your App                    Zet API                   Bridge Protocol
   │                           │                          │
   ├── GET /transfer/chains ──►│                          │
   │◄── Chain + token list ────┤                          │
   │                           │                          │
   ├── POST /transfer/quote ──►│── Find route ───────────►│
   │◄── Quote + bridge info ───┤◄── Best bridge ──────────┤
   │                           │                          │
   ├── POST /transfer/execute ►│                          │
   │                           │── Approve + bridge ──► Source Chain
   │                           │                    Bridge relay ──► Dest Chain
   │                           │── Poll status ──────────►│
   │                           │                          │
   │◄── Webhook: transfer.completed ◄─────────────────────┤
   │                           │                          │

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Supported chains

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Source chains (send from)

ChainChain IDTokens
Base8453ETH, USDC, CNGN, cbBTC
BSC56BNB, USDC, USDT, CNGN

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Destination chains (send to)

ChainChain ID
Base8453
BSC56
Ethereum1
Polygon137
Arbitrum42161
Avalanche43114
Solana1151111081099710
You can also query supported chains dynamically via GET /transfer/chains.

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Step 1: Get a transfer quote

Transfer 100 USDC from Base to Ethereum: 
const quote = await fetch('https://api.zet.money/v1/transfer/quote', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': process.env.ZET_API_KEY,
  },
  body: JSON.stringify({
    fromChain: 'base',
    toChain: 'ethereum',
    token: 'USDC',
    toToken: 'USDC',              // Same token on destination
    amount: '100',
    destinationAddress: '0x742d35Cc6634C0532925a3b844Bc9e7595f5bA16',
  }),
}).then(r => r.json());

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Bridge + swap

Transfer USDC from Base and receive ETH on Ethereum: 
const quote = await fetch('https://api.zet.money/v1/transfer/quote', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': process.env.ZET_API_KEY,
  },
  body: JSON.stringify({
    fromChain: 'base',
    toChain: 'ethereum',
    token: 'USDC',
    toToken: 'ETH',              // Different token on destination
    amount: '100',
    destinationAddress: '0x742d35Cc...',
  }),
}).then(r => r.json());

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Quote response

{
  "success": true,
  "data": {
    "quoteId": "qt_01H8X6abc",
    "fromChain": "base",
    "toChain": "ethereum",
    "fromToken": "USDC",
    "toToken": "USDC",
    "fromAmount": "100",
    "toAmount": "99.85",
    "fees": {
      "platformFee": "0.032",
      "platformFeeFiat": "50",
      "bridgeFee": "0.15",
      "totalFee": "0.182"
    },
    "route": {
      "steps": 2,
      "estimatedTime": "2-5 minutes",
      "bridge": "Stargate"
    },
    "expiresAt": "2026-03-02T10:05:00Z"
  }
}

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Fee breakdown

FeeAmountDescription
Platform fee50 NGN (in source token)Zet cross-chain fee
Bridge feeVariableSet by the bridge protocol (Stargate, Across, etc.)

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Step 2: Execute the transfer

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Custodial

const transfer = await fetch('https://api.zet.money/v1/transfer/execute', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': process.env.ZET_API_KEY,
  },
  body: JSON.stringify({
    quoteId: quote.data.quoteId,
    walletId: 'wal_01H8X3abc',
    reference: `transfer_${transferId}`,
  }),
}).then(r => r.json());

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Non-custodial

const transfer = await fetch('https://api.zet.money/v1/transfer/execute', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': process.env.ZET_API_KEY,
  },
  body: JSON.stringify({
    quoteId: quote.data.quoteId,
    sourceAddress: '0x742d35Cc...',
    reference: `transfer_${transferId}`,
  }),
}).then(r => r.json());

// User signs approval + bridge transaction
if (transfer.data.approvalData) {
  await userWallet.sendTransaction(transfer.data.approvalData);
}
await userWallet.sendTransaction(transfer.data.transactionData);

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Step 3: Monitor completion

Cross-chain transfers take longer than same-chain operations because they involve bridge relay confirmation on the destination chain.
BridgeEstimated Time
Stargate1-5 minutes
Across2-10 minutes
Hop5-20 minutes
Listen for the transfer.completed webhook: 
app.post('/webhooks/zet', (req, res) => {
  const { event, data } = req.body;

  if (event === 'transfer.completed') {
    console.log(`Transfer complete on ${data.chain}`);
    console.log(`TX: ${data.transactionHash}`);
  }

  if (event === 'transfer.failed') {
    // Funds typically remain on the source chain
    console.log(`Transfer failed: ${data.errorMessage}`);
  }

  res.status(200).send('OK');
});

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Common patterns

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Portfolio rebalancing

Move tokens between chains to rebalance a user’s portfolio: 
// Move 50 USDC from Base to BSC
const quote = await getTransferQuote({
  fromChain: 'base',
  toChain: 'bsc',
  token: 'USDC',
  toToken: 'USDC',
  amount: '50',
  destinationAddress: walletAddress, // Same address, different chain
});

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Multi-chain withdrawals

Let users withdraw to any supported chain: 
// User wants to withdraw 100 USDC to Polygon
const quote = await getTransferQuote({
  fromChain: 'base',
  toChain: 'polygon',
  token: 'USDC',
  toToken: 'USDC',
  amount: '100',
  destinationAddress: userPolygonAddress,
});

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Best practices

  1. Show estimated time — cross-chain transfers are slower than same-chain; manage user expectations
  2. Display the bridge protocol — users benefit from knowing which bridge is being used
  3. Handle stuck transactions — bridges can occasionally slow down; implement timeout alerts
  4. Prefer same-chain when possible — if both source and destination are on the same chain, use the Swap API instead
  5. Verify destination address format — ensure the address is valid for the destination chain (especially for Solana)
  6. Show fee breakdown — bridge fees vary significantly; transparency builds trust