What is a .xls file?

We read file headers, not extensions. Nothing gets uploaded.

What is it

The old binary format for Microsoft Excel (pre-2007). Still encountered in legacy files and some enterprise systems. Modern Excel uses XLSX instead.

Technical details

Full Name

Microsoft Excel Spreadsheet (Legacy)

MIME Type

application/vnd.ms-excel

Developer

Microsoft

Magic Bytes

D0 CF 11 E0

Safety

What opens it

Microsoft Excel

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