Saspiest HTML .NET SDK

using Aspose.Words;

var config = new Configuration { ClientId = "####-####-####-####-####",
   ClientSecret = "##################" };
var wordsApi = new WordsApi(config);

using var requestDocument = File.OpenRead("Input.html");
var requestCompressOptions = new CompressOptions()
{
    ImagesQuality = 75,
    ImagesReduceSizeFactor = 1
};
var compressDocumentRequest = new CompressDocumentOnlineRequest(requestDocument,
   requestCompressOptions);
var compressDocument = await wordsApi.CompressDocumentOnline(compressDocumentRequest);

var convertDocument =
   new ConvertDocumentRequest(compressDocument.Document.Values.First(), "html");
await wordsApi.ConvertDocument(convertDocument);