Native Token Swaps

The CoW Protocol SDK enables selling blockchain native tokens (ETH, MATIC, etc.) through the EthFlow contract. Since native tokens aren’t ERC-20 compliant, they require special handling for on-chain transactions.

How It Works

When selling native tokens:

An on-chain transaction is sent to the EthFlow contract
Native tokens are locked in the contract
An order is created in the CoW Protocol order book
Upon filling, the buyer receives their tokens
Unfilled orders can be cancelled to reclaim funds

Only selling native tokens is supported. To buy native tokens, trade for wrapped versions (e.g., WETH) first.

Using postSwapOrder (Automatic Detection)

The SDK automatically detects native token orders using the special marker address 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE and routes them through EthFlow.

import {
  SupportedChainId,
  OrderKind,
  TradeParameters,
  TradingSdk
} from '@cowprotocol/sdk-trading'
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
import { createPublicClient, http, privateKeyToAccount } from 'viem'
import { sepolia } from 'viem/chains'

const adapter = new ViemAdapter({
  provider: createPublicClient({
    chain: sepolia,
    transport: http('YOUR_RPC_URL')
  }),
  signer: privateKeyToAccount('YOUR_PRIVATE_KEY' as `0x${string}`)
})

const sdk = new TradingSdk({
  chainId: SupportedChainId.SEPOLIA,
  appCode: 'YOUR_APP_CODE',
}, {}, adapter)

const parameters: TradeParameters = {
  kind: OrderKind.SELL,
  sellToken: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE',
  sellTokenDecimals: 18,
  buyToken: '0x0625afb445c3b6b7b929342a04a22599fd5dbb59',
  buyTokenDecimals: 18,
  amount: '100000000000000000', // 0.1 ETH
}

const { orderId, txHash } = await sdk.postSwapOrder(parameters)

console.log('Order ID:', orderId)
console.log('Transaction hash:', txHash)

Using postSellNativeCurrencyOrder

For more control, use the dedicated postSellNativeCurrencyOrder method:

Method Signature

postSellNativeCurrencyOrder(
  params: TradeParameters,
  advancedSettings?: SwapAdvancedSettings
): Promise<{
  orderId: string
  txHash: string
  signingScheme: SigningScheme
  signature: string
  orderToSign: UnsignedOrder
}>

Example

import {
  SupportedChainId,
  OrderKind,
  TradeParameters,
  TradingSdk
} from '@cowprotocol/sdk-trading'
import { ViemAdapter } from '@cowprotocol/sdk-viem-adapter'
import { createPublicClient, http, privateKeyToAccount } from 'viem'
import { sepolia } from 'viem/chains'

const adapter = new ViemAdapter({
  provider: createPublicClient({
    chain: sepolia,
    transport: http('YOUR_RPC_URL')
  }),
  signer: privateKeyToAccount('YOUR_PRIVATE_KEY' as `0x${string}`)
})

const sdk = new TradingSdk({
  chainId: SupportedChainId.SEPOLIA,
  appCode: 'YOUR_APP_CODE',
}, {}, adapter)

const parameters: TradeParameters = {
  kind: OrderKind.SELL,
  sellToken: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE',
  sellTokenDecimals: 18,
  buyToken: '0x0625afb445c3b6b7b929342a04a22599fd5dbb59',
  buyTokenDecimals: 18,
  amount: '100000000000000000', // 0.1 ETH
}

const result = await sdk.postSellNativeCurrencyOrder(parameters)

console.log('Order created:', result.orderId)
console.log('Transaction:', result.txHash)

// Wait for transaction confirmation
await adapter.provider.waitForTransactionReceipt({ hash: result.txHash })
console.log('Transaction confirmed!')

Complete Example with Quote

import {
  TradingSdk,
  SupportedChainId,
  OrderKind,
  TradeParameters,
} from '@cowprotocol/sdk-trading'
import { parseEther } from 'viem'

const sdk = new TradingSdk({
  chainId: SupportedChainId.MAINNET,
  appCode: 'YOUR_APP_CODE',
}, {}, adapter)

const parameters: TradeParameters = {
  kind: OrderKind.SELL,
  sellToken: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE',
  sellTokenDecimals: 18,
  buyToken: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // USDC
  buyTokenDecimals: 6,
  amount: parseEther('1').toString(), // 1 ETH
}

// Step 1: Get a quote
const { quoteResults } = await sdk.getQuote(parameters)

const expectedUSDC = quoteResults.amountsAndCosts.afterSlippage.buyAmount
const ethAmount = parseEther('1')

console.log(`Selling ${ethAmount} ETH`)
console.log(`Expected to receive at least: ${expectedUSDC} USDC`)

// Step 2: Create the order
if (confirm('Proceed with the trade?')) {
  const { orderId, txHash } = await sdk.postSellNativeCurrencyOrder(parameters)

  console.log('Order ID:', orderId)
  console.log('Transaction hash:', txHash)

  await adapter.provider.waitForTransactionReceipt({ hash: txHash })
  console.log('Order created successfully!')
}

Order Kinds for Native Tokens

SELL Orders (Supported)
BUY Orders (Limited)

const parameters: TradeParameters = {
  kind: OrderKind.SELL,
  sellToken: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE',
  sellTokenDecimals: 18,
  buyToken: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
  buyTokenDecimals: 6,
  amount: '1000000000000000000', // 1 ETH
}

const parameters: TradeParameters = {
  kind: OrderKind.BUY,
  sellToken: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE',
  sellTokenDecimals: 18,
  buyToken: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
  buyTokenDecimals: 6,
  amount: '1000000000', // 1000 USDC
}

Gas Cost Considerations

Native token orders require on-chain transactions, making them significantly more expensive than regular orders:

Operation	Gas Usage	Estimated Cost
EthFlow order creation	~150,000-200,000	~ $15-$ 20
Regular orders	0 gas	Free (off-chain)
Cancellation	~50,000-70,000 gas	~ $5-$ 7

Always ensure you have enough ETH for gas in addition to the amount you’re selling.

Cancelling Native Token Orders

import { TradingSdk } from '@cowprotocol/sdk-trading'

const sdk = new TradingSdk({
  chainId: SupportedChainId.MAINNET,
  appCode: 'YOUR_APP_CODE',
}, {}, adapter)

const { orderId, txHash } = await sdk.postSellNativeCurrencyOrder(parameters)

// Try off-chain cancellation first
try {
  await sdk.offChainCancelOrder({ orderUid: orderId })
  console.log('Order cancelled (soft)')
} catch (error) {
  // Fall back to on-chain cancellation (refunds locked ETH)
  const cancelTxHash = await sdk.onChainCancelOrder({ orderUid: orderId })
  console.log('Cancellation transaction:', cancelTxHash)

  await adapter.provider.waitForTransactionReceipt({ hash: cancelTxHash })
  console.log('Order cancelled and ETH refunded')
}

Advanced: Custom EthFlow Parameters

import { SwapAdvancedSettings, SigningScheme } from '@cowprotocol/sdk-trading'

const advancedSettings: SwapAdvancedSettings = {
  quoteRequest: {
    signingScheme: SigningScheme.EIP1271,
    onchainOrder: true,
    verificationGasLimit: 0,
    validFor: 3600, // 1 hour
  },
}

const { orderId, txHash } = await sdk.postSellNativeCurrencyOrder(
  parameters,
  advancedSettings
)

Common Chains and Native Tokens

Chain	Native Token	Address to Use
Ethereum	ETH	`0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE`
Gnosis	xDAI	`0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE`
Arbitrum	ETH	`0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE`
Sepolia	ETH	`0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE`

Best Practices

Verify sufficient balance for both the order amount and gas fees
Use OrderKind.SELL for better predictability with native tokens
Wait for transaction confirmation before querying order status
Consider wrapping to WETH for smaller amounts where gas costs might exceed savings
Monitor gas prices before executing native token orders

Next Steps

Learn about Creating Swap Orders for regular ERC-20 trades
See Order Management to track and cancel orders
Explore Token Approvals for ERC-20 approval management

Getting Started

Concepts

Guides

Advanced

Examples

API Reference

Migration

Native Token Swaps

Native Token Swaps

How It Works

Using postSwapOrder (Automatic Detection)

Using postSellNativeCurrencyOrder

Method Signature

Example

Complete Example with Quote

Order Kinds for Native Tokens

Gas Cost Considerations

Cancelling Native Token Orders

Advanced: Custom EthFlow Parameters

Common Chains and Native Tokens

Best Practices

Next Steps

​Native Token Swaps

​How It Works

​Using postSwapOrder (Automatic Detection)

​Using postSellNativeCurrencyOrder

​Method Signature

​Example

​Complete Example with Quote

​Order Kinds for Native Tokens

​Gas Cost Considerations

​Cancelling Native Token Orders

​Advanced: Custom EthFlow Parameters

​Common Chains and Native Tokens

​Best Practices

​Next Steps

Native Token Swaps

How It Works

Using postSwapOrder (Automatic Detection)

Using postSellNativeCurrencyOrder

Method Signature

Example

Complete Example with Quote

Order Kinds for Native Tokens

Gas Cost Considerations

Cancelling Native Token Orders

Advanced: Custom EthFlow Parameters

Common Chains and Native Tokens

Best Practices

Next Steps