> ## Documentation Index
> Fetch the complete documentation index at: https://docs.base.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Base Builder Codes

> Attribute onchain activity to your app, wallet or agent with Builder Codes.

## What Are Builder Codes

Base Builder Codes are an ERC-721 NFT collection where unique codes (e.g. "abc123") are minted to help identify builders onchain.

Each code has associated metadata. Onchain metadata primarily includes a "payout address" where each code declares where potential rewards should be sent to. Offchain metadata includes more details about the app including its name and site.

<Tip>
  Get your Builder Code by registering on [base.dev](https://base.dev/). You can find your code under **Settings** → **Builder Code**.
</Tip>

## Integration Guides

<CardGroup cols={3}>
  <Card title="For App Developers" icon="code" href="/apps/builder-codes/app-developers">
    Integrate Builder Codes using Wagmi or Viem
  </Card>

  <Card title="For Wallet Developers" icon="wallet" href="/apps/builder-codes/wallet-developers">
    Implement the dataSuffix capability
  </Card>

  <Card title="For Agent Developers" icon="robot" href="/apps/builder-codes/agent-developers">
    Attribute your AI agent's transactions via the API
  </Card>
</CardGroup>

## Benefits

* **Rewards:** If your app drives transactions, Builder Codes let Base automatically attribute that usage back to you, unlocking rewards as the program expands.
* **Analytics:** Reliably track onchain usage, user acquisition, and conversion metrics in Base.dev.
* **Visibility:** Apps with Builder Codes can show up in discovery surfaces like App Leaderboards, Base App store, and ecosystem spotlights.

## FAQ

### Do I Need to Modify My Smart Contracts?

**No.** The attribution suffix is appended to the end of transaction calldata. Smart contracts execute normally and ignore the extra data. Attribution is extracted by offchain indexers after the fact.

This means:

* Any existing smart contract automatically supports ERC-8021
* No upgrades or redeployments required
* Zero impact on contract execution

### How Much Additional Gas Do Builder Codes Cost?

The ERC-8021 suffix adds a negligible amount of gas to each transaction at 16 gas per non-zero byte.

### Will Builder Codes Expose My Identity?

**No.** Builder Codes only associate transactions with your application—they don't expose any wallet information that isn't already public onchain.

### Can I Use ERC-8021 with Externally Owned Accounts (EOAs)?

**Yes.** ERC-8021 works with both EOAs and smart contract wallets.

### How Do I Verify That My Transaction Was Properly Attributed?

**1. Check base.dev**

* Visit [base.dev](https://base.dev)
* Select **Onchain** from the transaction type dropdown
* Under the Total Transactions section, attribution counts increment when transactions with your code are processed

**2. Use a Block Explorer (Basescan, Etherscan, etc.)**

* Find your transaction hash
* View the input data field
* Verify the last 16 bytes are the `8021` repeating
* Decode the suffix to confirm your Builder Code is present

**3. Open Source Tools**

* Use the [Builder Code Validation](https://builder-code-checker.vercel.app/) tool
* Select transaction type
* Enter the transaction or UserOperation hash
* Click the **Check Attribution** button

### Which Wallets Currently Support ERC-8021?

**EOAs:**

All EOA wallets support `dataSuffix` by default.

**Smart Wallets:**

Wallets supporting ERC-5792 can use the `DataSuffixCapability` for clean suffix appending.

<Accordion title="Example Code">
  ```javascript theme={null}
  await wallet.sendCalls({
    calls: [
      // your transaction calls
    ],
    capabilities: {
      dataSuffix: {
        value: "0x07626173656170700080218021802180218021802180218021",
        optional: true
      }
    }
  });
  ```
</Accordion>

**Embedded Wallets:**

* **Privy** - Embedded wallet solution with ERC-8021 capability
* **Turnkey** - Infrastructure for programmatic wallets

## Additional Resources

* [Official ERC-8021 Proposal](https://eip.tools/eip/8021)
* [Builder Code Validation Tool](https://builder-code-checker.vercel.app/)

## Give Feedback!

<Note>
  Base is constantly working to improve the Builder Codes experience. If you
  have any feedback, please let the team know [here](https://t.co/zwvtmXXzGz).
</Note>