using System; using System.Web; using System.IO; public class DownloadHandler : IHttpHandler { public void ProcessRequest (HttpContext context) { // 1. Get the file path string filePath = context.Server.MapPath("~/App_Data/Reports/MyFile.pdf"); FileInfo file = new FileInfo(filePath); if (file.Exists) { // 2. Clear the response buffer context.Response.Clear(); context.Response.ClearHeaders(); context.Response.Buffer = true; // 3. Set the Content-Disposition to 'attachment' // This forces the 'Save As' dialog instead of opening in browser context.Response.AddHeader("Content-Disposition", "attachment; filename=\"" + file.Name + "\""); // 4. Set the Content-Length so the browser shows a progress bar context.Response.AddHeader("Content-Length", file.Length.ToString()); // 5. Set the correct MIME type context.Response.ContentType = "application/pdf"; // 6. Transmit the file context.Response.TransmitFile(file.FullName); // 7. End the response context.Response.Flush(); context.Response.End(); } else { context.Response.StatusCode = 404; context.Response.Write("File not found."); } } public bool IsReusable { get { return false; } } } Use code with caution. Best Practices for File Handlers
Do the files live on a or cloud storage (Azure/AWS)? download file from handler c#
If you are dealing with exceptionally large files, the standard response might time out. You can increase the timeout in your web.config or manually chunk the file output using a buffer. using System; using System
Use context.Request.QueryString["id"] to look up file paths in a database rather than passing raw paths in the URL for better security. Set the Content-Disposition to 'attachment' // This forces