Returning plain text or other arbitary file in ASP.net

If you only want to return plain text like that I would use an ashx file (Generic Handler in VS). Then just add the text you want to return in the ProcessRequest method.

public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "text/plain";
        context.Response.Write("This is plain text");
    }

This removes the added overhead of a normal aspx page.

Example in C# (for VB.NET just remove the end ;):

Response.ContentType = "text/plain";
Response.Write("This is plain text");

You may want to call Response.Clear beforehand in order to ensure there are no headers or content in the buffer already.

You should use Response property of Page class:

Response.Clear();
Response.ClearHeaders();
Response.AddHeader("Content-Type", "text/plain");
Response.Write("This is plain text");
Response.End();