Tutorial: Interacting with Angle Protocol's Transmuter for Fee-less Stablecoin Swaps

One of the most powerful features of the Angle Protocol is its Transmuter module. It's a mechanism that allows for highly efficient, zero-slippage swaps between different collateral assets backing the agEUR stablecoin. Let's explore how it works from a developer's perspective.

The Concept: A Stability and Arbitrage Hub
The Transmuter holds a portion of the protocol's collateral. It is designed to always maintain the peg: 1 agEUR = 1 Euro worth of collateral. It allows anyone to swap agEUR for an equivalent value of a collateral asset (or vice-versa) at a 1:1 ratio, with zero fees or slippage.

This creates a powerful arbitrage opportunity that keeps agEUR stable. If agEUR trades at €0.99 on Uniswap, an arbitrageur can buy it, swap it for €1.00 of collateral in the Transmuter, and pocket the difference, pushing the price back up.

Interacting with the Transmuter (Conceptual Solidity)
Imagine you want to build a dApp that automatically rebalances a user's portfolio by swapping agEUR for USDC when needed.

solidity
// This is a simplified example
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IAngleTransmuter {
// Swaps a collateral token for agEUR
function swapFor(address collateral, uint256 amountIn) external;

// Swaps agEUR for a collateral token
function swapFrom(address collateral, uint256 amountIn) external;

// Gets the current exchange rate for a collateral
function getRate(address collateral) external view returns (uint256);

}

contract Rebalancer {
IAngleTransmuter public transmuter;
IERC20 public agEUR;
IERC20 public USDC;

constructor(address _transmuter, address _agEUR, address _usdc) {
    transmuter = IAngleTransmuter(_transmuter);
    agEUR = IERC20(_agEUR);
    USDC = IERC20(_usdc);
}

// Swap exactly 100 agEUR for USDC
function swapAgEURForUSDC() external {
    uint256 amountToSwap = 100 * 1e18;
    agEUR.approve(address(transmuter), amountToSwap);

    // This call will swap 100 agEUR for ~$100 worth of USDC
    transmuter.swapFrom(address(USDC), amountToSwap);
}

}
By integrating directly with modules like the Transmuter, developers can leverage Angle's deep liquidity and stability mechanisms to build more efficient financial products. For full contract ABIs and addresses, the official community documentation is the definitive Guide.