# defineAlchemyChain | @account-kit/infra

> Overview of the defineAlchemyChain function from @account-kit/infra

> For the complete documentation index, see [llms.txt](/docs/llms.txt).

{/* This file is auto-generated by TypeDoc. Do not edit manually. */}

```ts
function defineAlchemyChain(params): Chain;
```

Defined in: [account-kit/infra/src/chains.ts:57](https://github.com/alchemyplatform/aa-sdk/blob/main/account-kit/infra/src/chains.ts#L57)

Defines an Alchemy chain configuration by adding an Alchemy-specific RPC base URL to the chain's RPC URLs.

## Example

```ts
import { defineAlchemyChain } from "@account-kit/infra";
import { sepolia } from "viem/chains";

const chain = defineAlchemyChain({
  chain: sepolia,
  rpcBaseUrl: "https://eth-sepolia.g.alchemy.com/v2",
});
```

## Parameters

<table>
  <thead>
    <tr>
      <th align="left">Parameter</th>
      <th align="left">Type</th>
      <th align="left">Description</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td>
        `params`
      </td>

      <td>
        \{ `chain`: [`Chain`](https://viem.sh); `rpcBaseUrl`: `string`; }
      </td>

      <td>
        The parameters for defining the Alchemy chain
      </td>
    </tr>

    <tr>
      <td>
        `params.chain`
      </td>

      <td>
        [`Chain`](https://viem.sh)
      </td>

      <td>
        The original chain configuration
      </td>
    </tr>

    <tr>
      <td>
        `params.rpcBaseUrl`
      </td>

      <td>
        `string`
      </td>

      <td>
        The Alchemy-specific RPC base URL
      </td>
    </tr>

  </tbody>
</table>

## Returns

[`Chain`](https://viem.sh)

The updated chain configuration with the Alchemy RPC URL added