What to set as mimetype for CSV files to open in spreadsheet applications

Question

My application lets users download their data as CSV files. These are supposed to open in spreadsheet applications. On a Linux system, I get prompted correctly to open with

Answer 1

Try this:

Content-Type: text/csv; name="filename.csv"
Content-Disposition: attachment; filename="filename.csv"

In Windows browsers the MIME type is ignored after the file is downloaded and only file name extension is used to determine the corresponding application.

Also, making .CSV file open in Excel correctly is hard, because the default separator is taken from Regional settings on the machine on which the CSV is opened. Furthermore, the encoding is not determined from the file content or MIME type, so any non-ASCII characters are hard to get working.