Use GetBucketWebsite with an AWS SDK or CLI

                // Get the website configuration.
                GetBucketWebsiteRequest getRequest = new GetBucketWebsiteRequest()
                {
                    BucketName = bucketName,
                };
                GetBucketWebsiteResponse getResponse = await client.GetBucketWebsiteAsync(getRequest);
                Console.WriteLine($"Index document: {getResponse.WebsiteConfiguration.IndexDocumentSuffix}");
                Console.WriteLine($"Error document: {getResponse.WebsiteConfiguration.ErrorDocument}");

bool AwsDoc::S3::getWebsiteConfig(const Aws::String &bucketName,
                                  const Aws::S3::S3ClientConfiguration &clientConfig) {
    Aws::S3::S3Client s3Client(clientConfig);

    Aws::S3::Model::GetBucketWebsiteRequest request;
    request.SetBucket(bucketName);

    Aws::S3::Model::GetBucketWebsiteOutcome outcome =
            s3Client.GetBucketWebsite(request);

    if (!outcome.IsSuccess()) {
        const Aws::S3::S3Error &err = outcome.GetError();

        std::cerr << "Error: GetBucketWebsite: "
                  << err.GetMessage() << std::endl;
    } else {
        Aws::S3::Model::GetBucketWebsiteResult websiteResult = outcome.GetResult();

        std::cout << "Success: GetBucketWebsite: "
                  << std::endl << std::endl
                  << "For bucket '" << bucketName << "':"
                  << std::endl
                  << "Index page : "
                  << websiteResult.GetIndexDocument().GetSuffix()
                  << std::endl
                  << "Error page: "
                  << websiteResult.GetErrorDocument().GetKey()
                  << std::endl;
    }

    return outcome.IsSuccess();
}

The following command retrieves the static website configuration for a bucket named amzn-s3-demo-bucket:

aws s3api get-bucket-website --bucket amzn-s3-demo-bucket

Output:

{
    "IndexDocument": {
        "Suffix": "index.html"
    },
    "ErrorDocument": {
        "Key": "error.html"
    }
}

Get the website configuration.

import {
  GetBucketWebsiteCommand,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Log the website configuration for a bucket.
 * @param {{ bucketName }}
 */
export const main = async ({ bucketName }) => {
  const client = new S3Client({});

  try {
    const response = await client.send(
      new GetBucketWebsiteCommand({
        Bucket: bucketName,
      }),
    );
    console.log(
      `Your bucket is set up to host a website with the following configuration:\n${JSON.stringify(response, null, 2)}`,
    );
  } catch (caught) {
    if (
      caught instanceof S3ServiceException &&
      caught.name === "NoSuchWebsiteConfiguration"
    ) {
      console.error(
        `Error from S3 while getting website configuration for ${bucketName}. The bucket isn't configured as a website.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while getting website configuration for ${bucketName}.  ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

Example 1: This command returns the details of the static website configurations of the given S3 bucket.

Get-S3BucketWebsite -BucketName 'amzn-s3-demo-bucket'