Cross-Chain Transfer Guide

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

Overview

Cross-chain transfers use Zet’s multi-chain routing infrastructure 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 ◄─────────────────────┤
   │                           │                          │

Supported chains

Source chains (send from)

Chain	Chain ID	Tokens
Base	8453	ETH, USDC, CNGN, cbBTC
BSC	56	BNB, USDC, USDT, CNGN

Destination chains (send to)

Chain	Chain ID
Base	8453
BSC	56
Ethereum	1
Polygon	137
Arbitrum	42161
Avalanche	43114
Solana	1151111081099710

You can also query supported chains dynamically via GET /transfer/chains.

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());

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());

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": "Bridge Protocol"
    },
    "expiresAt": "2026-03-02T10:05:00Z"
  }
}

Fee breakdown

Fee	Amount	Description
Platform fee	50 NGN (in source token)	Zet cross-chain fee
Bridge fee	Variable	Set by the bridge protocol

Step 2: Execute the transfer

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());

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);

Step 3: Monitor completion

Cross-chain transfers take longer than same-chain operations because they involve bridge relay confirmation on the destination chain.

Bridge	Estimated Time
Fast bridges	1-5 minutes
Standard bridges	2-10 minutes
Slow bridges	5-20 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');
});

Common patterns

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
});

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,
});

Best practices

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

​Cross-Chain Transfer Guide

​Overview

​Supported chains

​Source chains (send from)

​Destination chains (send to)

​Step 1: Get a transfer quote

​Bridge + swap

​Quote response

​Fee breakdown

​Step 2: Execute the transfer

​Custodial

​Non-custodial

​Step 3: Monitor completion

​Common patterns

​Portfolio rebalancing

​Multi-chain withdrawals

​Best practices

Cross-Chain Transfer Guide

Overview

Supported chains

Source chains (send from)

Destination chains (send to)

Step 1: Get a transfer quote

Bridge + swap

Quote response

Fee breakdown

Step 2: Execute the transfer

Custodial

Non-custodial

Step 3: Monitor completion

Common patterns

Portfolio rebalancing

Multi-chain withdrawals

Best practices