# Koi Paymaster Service

By utilizing [zkSync Era account abstraction paymasters](https://era.zksync.io/docs/reference/concepts/account-abstraction.html#paymasters), Mute allows for gas to be paid with other tokens instead of ETH. 

{% hint style="info" %}
Instead of paying a transaction fee of $0.40 with ETH, the user can opt in to use any of the supported tokens below. The conversion price is based on the token/ETH LP pool on the Mute Switch.
{% endhint %}

This is a free to use service.

## Integration

You can easily integrate the Mute Paymaster into your dApp - [Official documentation](https://era.zksync.io/docs/api/js/features.html)\
\
[Official Paymaster Address](https://era.zksync.network/address/0x4ae2Ba9A5C653038C6d2F5D9F80B28011A454597)

```jsx
const PAYMASTER_ADDRESS = '0x4ae2Ba9A5C653038C6d2F5D9F80B28011A454597'
...
// approve the token for spending via the paymaster
... 
const greeting = "a new greeting";
const tx = await greeter.populateTransaction.setGreeting(greeting);
const gasPrice = await sender.provider.getGasPrice();
const gasLimit = await greeter.estimateGas.setGreeting(greeting);

const paymasterParams = utils.getPaymasterParams(testnetPaymaster, {
  type: "ApprovalBased",
  TOKEN_ADDRESS,
  minimalAllowance: ethers.BigNumber.from(1),,
  innerInput: new Uint8Array(),
});

const sentTx = await sender.sendTransaction({
  ...tx,
  maxFeePerGas: gasPrice,
  maxPriorityFeePerGas: BigNumber.from(0),
  gasLimit,
  customData: {
    gasPerPubdata: utils.DEFAULT_GAS_PER_PUBDATA_LIMIT,
    paymasterParams,
  },
});
```

## Supported Tokens

* [USDC](https://explorer.zksync.io/address/0x3355df6D4c9C3035724Fd0e3914dE96A5a83aaf4)
* [WBTC](https://explorer.zksync.io/address/0xBBeB516fb02a01611cBBE0453Fe3c580D7281011)
* [MUTE](https://explorer.zksync.io/address/0x0e97C7a0F8B2C9885C8ac9fC6136e829CbC21d42)


---

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