FileHint
JAEN

.xlsx

High risk

Microsoft Excel Workbook (Open XML)

Excel's default format since 2007. Under the hood, a ZIP bundle of XML and media — also readable by Numbers and LibreOffice Calc.

MIME types

  • application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Category

document

What opens this file

  • Excel
  • Google Sheets
  • Numbers
  • LibreOffice Calc

How to open by OS

Windows

  • Excel, Google Sheets.

Mac

  • Excel for Mac, Numbers, LibreOffice Calc.

Linux

  • LibreOffice Calc.

Ios

  • Excel Mobile, Numbers.

Android

  • Excel Mobile, Google Sheets.

Safety notes

  • Watch out for CSV Injection via formula cells, and for data exfiltration via external workbook links.
  • Always open untrusted xlsx in Protected View; approve external links only after review.

Common mistakes

  • Mixed-type columns trigger auto-conversion that drops leading zeros and misreads dates. Import as text and parse deliberately.
  • Pivot-table caches can balloon workbooks to hundreds of megabytes — clean before sharing.

Related extensions

References