lookup> .xlsx

.XLSX·File Extension

Excel Spreadsheet — Microsoft Excel workbook based on Office Open XML.

Documentapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Quick facts

Extension.xlsx

File typeExcel Spreadsheet

MIME typeapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheet

CategoryDocument

Charset—

CompressibleNo

Format familyxlsx

What is .xlsx

What is a .xlsx file?

A .xlsx file is a Excel Spreadsheet — Microsoft Excel workbook based on Office Open XML.

In the mime-db registry it maps to application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, and it is marked as non-compressible. When serving .xlsx over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to application/vnd.openxmlformats-officedocument.spreadsheetml.sheet — and is delivered over HTTP via the Content-Type header.

How to open .xlsx files

Use Microsoft Excel or LibreOffice to open and edit .xlsx files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Common software that reads/writes .xlsx:

Microsoft ExcelLibreOfficeGoogle Sheets

Relation chain

.xlsxextension of

format

xlsxserved as

mime type

application/vnd.openxmlformats-officedocument.spreadsheetml.sheetsent via header

http header

Related extensions

Related MIME types

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

.xlsx

Common uses

Reports and letters
Spreadsheets and budgets
Presentations
Ebooks

How to edit .xlsx files

Open the file with Microsoft Excel, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .xlsx files

Create a new file and save it with the .xlsx extension, or export this format from Microsoft Excel.

Frequently asked questions

What programs can open .xlsx files?

Common options include Microsoft Excel, LibreOffice, Google Sheets. You can also open many of these files with built-in viewers or a browser.

How do I create a .xlsx file?

Create a new file in any text editor or the app that owns the format and save it with the .xlsx extension.

What is the relationship between .xlsx and the application/vnd.openxmlformats-officedocument.spreadsheetml.sheet MIME type?

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet is the media type identifier used for .xlsx files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-09-13

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