I am working on a Flutter application, and I need to download a ZIP file from a public server using an HTTP GET request. The URL is something like: “https://example.com/file.zip”.

However, when I try to download the file from the web version of my app, the browser blocks the request due to CORS (Cross-Origin Resource Sharing) restrictions. The server does not include the Access-Control-Allow-Origin header in its response.

Here’s the basic structure of my current code:

import 'package:http/http.dart' as http;
import 'dart:html' as html;
// import 'dart:io';

Future<void> downloadZipFileWidget() async {
  const String url = 'https://example/file.zip';
  const String savePath = 'file.zip';
  try {
    final response = await http.get(Uri.parse(url));

    if (response.statusCode == 200) {
         final fileBytes = response.bodyBytes;
      print('File downloaded successfully');
        createDownloadLink(fileBytes, savePath);
             print('File saved to $savePath');
    } else {
      print('Error: ${response.statusCode}');
    }
  } catch (e) {
    print('Error: $e');
  }
}

void createDownloadLink(List<int> bytes, String fileName) {
  final blob = html.Blob([bytes]);
  final url = html.Url.createObjectUrlFromBlob(blob);
  final anchor = html.AnchorElement(href: url)
  ..target = 'blank'
  ..download = fileName
  ..click();
  html.Url.revokeObjectUrl(url);
}

And I call to the function from another “.dart” file.

when running on the web, I encounter the CORS issue.

Question:

What are the best ways to bypass CORS restrictions for downloading files in a Flutter Web app?
Are there proxy services, or should I implement my own proxy server?
Is there any way to work directly with the server without needing CORS modifications?