Thanks for your reply! Both the Excel and CSV exports produce a .CSV file, and it’s just that the Excel export is optimized for Excel whereas the CSV export always produces a comma-separated CSV file. The Export and CSV look similar/the same in most cases but may differ depending on the locale of the TestRail user and may also use something else than a comma as a delimiter (e.g., a semi-colon as some Excel environments expect this). We chose the CSV format for Excel as well because CSV files work with every Excel version and also other spreadsheet applications such as Google Spreadsheets or Numbers on the Mac. Hope this helps!