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

# DeFi integration

> Port AMMs, liquidity pools, and DeFi protocols to Arc using USDC as the canonical pool token and native gas asset.

For DeFi protocols on Arc, use the ERC-20 USDC interface at
`0x3600000000000000000000000000000000000000` for all pool accounting, token
addresses, and reserve math. Arc's native USDC has a
[built-in ERC-20 interface](/arc/concepts/stablecoin-native-model) at that
address, so no WETH-style adapter contract is needed.

## Key differences for DeFi protocols

Three Arc design decisions affect every DeFi porting decision:

| Concern                                     | Arc behavior                                                                                                                                                                                                                      | Impact on DeFi protocols                                                                                                                                                                                                                                                                                              |
| :------------------------------------------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **One balance, two decimal views**          | Native USDC uses 18 decimals (`msg.value`, `address.balance`); the ERC-20 interface uses 6 decimals (`balanceOf`, pool math). Both views draw from the same underlying balance.                                                   | Use 6-decimal ERC-20 values exclusively in pool invariant math. Mixing 18-decimal native values with 6-decimal ERC-20 values breaks constant-product calculations by a factor of 10<sup>12</sup>. Do not pair the native interface against the ERC-20 interface as two separate pool tokens; they are the same asset. |
| **No protocol adapter needed**              | Native USDC has a built-in ERC-20 interface at `0x3600000000000000000000000000000000000000`. No WETH-style adapter is required. See [EVM differences](/arc/references/evm-differences) for the full list of protocol divergences. | Use the ERC-20 address directly as the pool pair token.                                                                                                                                                                                                                                                               |
| **Allowances do not gate native transfers** | ERC-20 `approve` and `allowance` control only the `transferFrom` path. Native transfers (`msg.value`, direct sends) bypass the allowance check entirely.                                                                          | Pool sweep logic that relies on allowance limits does not protect the native balance.                                                                                                                                                                                                                                 |

## What you need

Each integration guide in this section requires the following:

| Requirement                    | Details                                                                                                                        |
| :----------------------------- | :----------------------------------------------------------------------------------------------------------------------------- |
| RPC access                     | `https://rpc.testnet.arc.io`                                                                                                   |
| Chain ID                       | `5042002` (testnet)                                                                                                            |
| USDC ERC-20 contract           | [`0x3600000000000000000000000000000000000000`](https://testnet.arcscan.app/address/0x3600000000000000000000000000000000000000) |
| Existing EVM contract codebase | A Solidity codebase to port to Arc                                                                                             |

## Integration guides

<CardGroup cols={2}>
  <Card title="AMM and pools" icon="chart-mixed" href="/integrate/defi/amm-and-pools">
    Port liquidity pools and AMM contracts to Arc using the ERC-20 USDC address
    as the canonical pool token.
  </Card>
</CardGroup>