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

# Constants Reference

> USDC contract addresses and chain ID constants exported by the Mandate SDK for mainnet and testnet networks.

## What constants does the SDK export?

The SDK exports two convenience objects: `USDC` for contract addresses and `CHAIN_ID` for network identifiers. These cover the four chains Mandate supports. Use them instead of hardcoding addresses and chain IDs in your agent code.

## USDC addresses

```typescript theme={null}
import { USDC } from '@mandate.md/sdk';

USDC.ETH_MAINNET  // 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
USDC.ETH_SEPOLIA  // 0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238
USDC.BASE_MAINNET // 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
USDC.BASE_SEPOLIA // 0x036CbD53842c5426634e7929541eC2318f3dCF7e
```

| Network     | Chain            | Address                                      |
| ----------- | ---------------- | -------------------------------------------- |
| **Mainnet** | Ethereum         | `0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48` |
| **Mainnet** | Base             | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` |
| **Testnet** | Ethereum Sepolia | `0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238` |
| **Testnet** | Base Sepolia     | `0x036CbD53842c5426634e7929541eC2318f3dCF7e` |

## Chain IDs

```typescript theme={null}
import { CHAIN_ID } from '@mandate.md/sdk';

CHAIN_ID.ETH_MAINNET  // 1
CHAIN_ID.ETH_SEPOLIA  // 11155111
CHAIN_ID.BASE_MAINNET // 8453
CHAIN_ID.BASE_SEPOLIA // 84532
```

| Network     | Chain            | ID         |
| ----------- | ---------------- | ---------- |
| **Mainnet** | Ethereum         | `1`        |
| **Mainnet** | Base             | `8453`     |
| **Testnet** | Ethereum Sepolia | `11155111` |
| **Testnet** | Base Sepolia     | `84532`    |

## Runtime keys and chain mapping

Your runtime key prefix determines which chains your agent can use.

| Key prefix    | Environment | Chains                         |
| ------------- | ----------- | ------------------------------ |
| `mndt_test_*` | Testnet     | Ethereum Sepolia, Base Sepolia |
| `mndt_live_*` | Production  | Ethereum Mainnet, Base Mainnet |

<Warning>
  Test keys only work with testnet chains. Live keys only work with mainnet chains. If you pass a testnet chain ID with a live key, the API returns a 422 error.
</Warning>

Use test keys during development. They connect to the same policy engine and return the same validation responses, but all transactions go to Sepolia testnets where tokens have no real value.

```typescript theme={null}
import { MandateClient, USDC, CHAIN_ID } from '@mandate.md/sdk';

const client = new MandateClient({
  runtimeKey: process.env.MANDATE_RUNTIME_KEY!, // mndt_test_* for testnet
});

const result = await client.validate({
  action: 'transfer',
  amount: '5',
  to: '0xRecipientAddress',
  token: 'USDC',
  chain: String(CHAIN_ID.BASE_SEPOLIA),
  reason: 'Test payment for development',
});
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Chain Reference" icon="arrow-right" href="/reference/chain-reference">
    Full chain support details, RPC endpoints, and block explorers.
  </Card>

  <Card title="SDK Overview" icon="arrow-right" href="/sdk/overview">
    Installation, exports, and quick start guide.
  </Card>
</CardGroup>