The new API has the .Exists() function call. Just make sure that you use the `GetBlockBlobReference`, which doesn't perform the call to the server. It makes the function as easy as:
```public static bool BlobExistsOnCloud(CloudBlobClient client, string containerName, string key) { return client.GetContainerReference(containerName) .GetBlockBlobReference(key) .Exists(); }

The new API has the .Exists() function call. Just make sure that you use the `GetBlockBlobReference`, which doesn't perform the call to the server. It makes the function as easy as:
public static bool BlobExistsOnCloud(CloudBlobClient client, string containerName, string key) { return client.GetContainerReference(containerName) .GetBlockBlobReference(key) .Exists(); }