Builder Codes

Category: Onchain Attribution Standard Chain: Base Standard: ERC-8021 URL: base.dev Docs: docs.base.org

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Overview

Builder Codes are Base's onchain attribution system. They let any app or protocol tag their transactions so Base can measure who's driving ecosystem activity. Built on the ERC-8021 attribution standard, they work like a transponder — appended to transactions to cryptographically prove participation in the onchain value chain without revealing user data.

When you register on base.dev, you get a Builder Code (e.g. bc_b7k3p9da). Append it to your transactions and Base tracks your contribution to the ecosystem.

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Why It Matters

• Chain-level attribution for all Base activity
• Onchain analytics in your base.dev dashboard
• Foundation for future rewards — Builder Codes are how Base measures contribution and will determine eligibility for reward distribution
• No user data exposed — attribution without compromising privacy

Builder Codes are described as "the only way Base measures contribution to the ecosystem."

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How It Works

Builder Codes use the dataSuffix parameter to append attribution data to transactions. The recommended approach is configuring it at the client level so all transactions are automatically tagged.

Wagmi Setup

Install ox, wagmi, and viem (v2.45.0+), then add dataSuffix to your Wagmi config:

import { createConfig, http } from "wagmi";
import { base } from "wagmi/chains";
import { Attribution } from "ox/erc8021";

const DATA_SUFFIX = Attribution.toDataSuffix({
  codes: ["YOUR-BUILDER-CODE"],
});

export const config = createConfig({
  chains: [base],
  transports: { [base.id]: http() },
  dataSuffix: DATA_SUFFIX,
});

All transactions through Wagmi hooks (useSendTransaction, useSendCalls) automatically include the code — no changes to components needed.

Viem Setup

Add dataSuffix when creating your wallet client:

import { createWalletClient, http } from "viem";
import { base } from "viem/chains";
import { Attribution } from "ox/erc8021";

const DATA_SUFFIX = Attribution.toDataSuffix({
  codes: ["YOUR-BUILDER-CODE"],
});

export const walletClient = createWalletClient({
  chain: base,
  transport: http(),
  dataSuffix: DATA_SUFFIX,
});

Privy

Privy provides a dataSuffix plugin that handles both EOA and ERC-4337 smart wallet transactions automatically.

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Verifying Attribution

1. base.dev — check the Onchain section under Total Transactions for attribution counts
2. Block explorer — find the transaction, check input data, verify the last 16 bytes are 8021 repeating
3. Open source tool — Builder Code Validation

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Adoption

Major platforms already implementing ERC-8021:

• Coinbase Retail
• Coinbase Base App
• Aerodrome
• Moonwell
• Privy

The Base App auto-appends Builder Codes to transactions users make in registered apps (mini apps, Base App browser) — no integration needed for that flow. Web and other clients require the dataSuffix integration.

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Sources

• base.dev
• docs.base.org
• Antonio GM announcement
• Builder Code Checker

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Last updated: 2026-03-11