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

# Lookup Address

> Get the ENS name for an Ethereum address

## Method Signature

```typescript theme={null}
align.blockchain.utils.lookupAddress(
  address: string,
  provider: JsonRpcProvider
): Promise<string | null>
```

## Parameters

<ParamField body="address" type="string" required>
  Ethereum address to look up
</ParamField>

<ParamField body="provider" type="JsonRpcProvider" required>
  Ethereum mainnet provider
</ParamField>

## Returns

Returns the primary ENS name as a string, or `null` if not set.

## Examples

<Tabs>
  <Tab title="TypeScript">
    ```typescript theme={null}
    import Align from "@tolbel/align";

    const align = new Align({
      apiKey: process.env.ALIGN_API_KEY!,
      environment: "sandbox",
    });

    const provider = align.blockchain.providers.getProvider("ethereum");

    const ensName = await align.blockchain.utils.lookupAddress(
      "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
      provider
    );

    if (ensName) {
      console.log(`Address has ENS: ${ensName}`);
      // Address has ENS: vitalik.eth
    } else {
      console.log("No ENS name set");
    }
    ```
  </Tab>

  <Tab title="JavaScript">
    ```javascript theme={null}
    const name = await align.blockchain.utils.lookupAddress(
      address,
      provider
    );
    console.log("ENS:", name);
    ```
  </Tab>
</Tabs>

### Display Friendly Names

```typescript theme={null}
async function formatAddress(address: string): Promise<string> {
  const provider = align.blockchain.providers.getProvider("ethereum");

  const ensName = await align.blockchain.utils.lookupAddress(address, provider);

  if (ensName) {
    return ensName; // vitalik.eth
  }

  // Truncate address for display
  return `${address.slice(0, 6)}...${address.slice(-4)}`; // 0xd8dA...6045
}
```

<Info>
  Not all addresses have ENS names. Only addresses with a primary ENS name set
  will return a value.
</Info>

## Related Methods

<CardGroup cols={2}>
  <Card title="Resolve Name" icon="globe" href="/docs/api/blockchain/utils/resolve-name">
    ENS to address
  </Card>

  <Card title="Validate Address" icon="check" href="/docs/api/blockchain/utils/is-valid-address">
    Check address format
  </Card>
</CardGroup>