Explanation: Metadata.Add example: // Add metadata to the dictionary by calling the Add method metadata.Add("docType", "textDocuments"); SetMetadataAsync example: // Set the blob's metadata. await blob.SetMetadataAsync(metadata); // Set the blob's properties. await blob.SetPropertiesAsync(); Reference: https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blob-properties-metadata