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Defined in ERC-8021
The dataSuffix capability allows apps to append arbitrary hex-encoded bytes to transaction calldata. This enables attribution tracking, allowing platforms to identify which app originated a transaction and distribute rewards accordingly.

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Parameters

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value
`0x${string}`
required
Hex-encoded bytes to append to the transaction calldata. This value is appended to the end of the calldata for each call in the batch.
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optional
boolean
When true, the wallet may ignore the capability if it doesn’t support it. When false or omitted, the wallet must support the capability or reject the request.

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Returns

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dataSuffix
object
The data suffix capability configuration for the specified chain.

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Example Usage

const capabilities = await provider.request({
  method: 'wallet_getCapabilities',
  params: [userAddress]
});

const dataSuffixSupport = capabilities["0x2105"]?.dataSuffix;

{
  "0x2105": {
    "dataSuffix": {
      "supported": true
    }
  }
}

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Error Handling

CodeMessageDescription
4100Data suffix not supportedWallet does not support data suffix functionality
5700DataSuffix capability requiredTransaction requires dataSuffix but wallet doesn’t support it

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How It Works

When a wallet receives a dataSuffix capability, the suffix is appended to userOp.callData. The suffix bytes are concatenated directly to the end of the calldata, making them available for onchain parsing and attribution.

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Use Cases

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Builder Codes Attribution

The primary use case for dataSuffix is Builder Codes attribution. Builder Codes are unique identifiers that allow apps to receive attribution for onchain activity they generate. 
import { Attribution } from "ox/erc8021";

// Example: Using Builder Code with dataSuffix.
// Using the ox/erc8021 package to generate the ERC-8021 suffix from your builder code.
const builderCodeSuffix = Attribution.toDataSuffix({
  codes: ['bc_foobar'], // Get your code from base.dev
});

await provider.request({
  method: "wallet_sendCalls",
  params: [{
    version: "1.0",
    chainId: "0x2105",
    from: userAddress,
    calls: [{
      to: contractAddress,
      value: "0x0",
      data: swapCallData
    }],
    capabilities: {
      dataSuffix: {
        value: builderCodeSuffix,
        optional: true
      }
    }
  }]
});
Register on base.dev to get your Builder Code for proper attribution.

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Best Practices

  1. Use with Builder Codes: Register on base.dev to get your Builder Code for proper attribution
  2. Set optional appropriately: Use optional: true if your app can function without attribution tracking
  3. Keep suffixes small: Larger suffixes increase gas costs
For wallet developers implementing dataSuffix support, see the For Wallet Developers section in the Builder Codes guide.