What is a .docx file?
Microsoft Word Open XML Document · Document · Microsoft · 2007
DOCX is the modern Word document format. It is really a zip archive of XML files, which makes it compact and open, and it is the default for letters, reports and essays across Word, Google Docs and LibreOffice.
What is a .docx file used for?
Since Word 2007, DOCX replaced the old binary DOC. Rename a DOCX to .zip and you can see the XML and images inside, which is why it is smaller and more resilient than the old format.
It stores formatted text, styles, tables, images and tracked changes. Google Docs, LibreOffice and Apple Pages all read and write it.
The older .doc format is the binary predecessor. Most apps still open it, but new documents should be DOCX.
Because a DOCX is a ZIP underneath, it shares the same first bytes as XLSX and PPTX, so a file identifier sees a ZIP archive and relies on the extension to tell which Office file it is. It also means a corrupted DOCX can report as a broken archive, and opening it in LibreOffice or Google Docs, which are more forgiving, often recovers it.
What opens a .docx file?
The .docx format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Microsoft Word
- LibreOffice
- Google Docs
- WordPad
macOS
- Word
- Pages
- LibreOffice
- Google Docs
Linux
- LibreOffice
- OnlyOffice
- Google Docs
Web
- Google Docs
- Office on the web
Open a .docx file step by step
- Confirm the file really is a .docx. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Microsoft Word or LibreOffice.
- On Mac, use Word or Pages.
- On Linux, try LibreOffice or OnlyOffice.
- Still stuck? Convert the .docx to PDF, which opens more widely.
Why can't I open my .docx file?
Almost always because no installed app understands DOCX. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .docx at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .docx file
You can convert a .docx file to PDF, TXT, ODT, RTF.
LibreOffice Writer opens DOCX and exports to PDF with File then Export as PDF, which keeps the layout exactly. Exporting to TXT throws away every image, table and style.
What is the .docx file signature (magic bytes)?
A .docx file starts with the hex bytes 50 4B 03 04, which read as PK.. in ASCII. Programs identify DOCX by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for DOCX. For a full breakdown, see the ZIP file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 50 4B 03 04 | 0 | PK.. | ZIP header (Office Open XML) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .docx file?
DOCX is the modern Word document format. It is really a zip archive of XML files, which makes it compact and open, and it is the default for letters, reports and essays across Word, Google Docs and LibreOffice.
Why won't my DOCX file open?
Common causes: a very old Word (before 2007) needs Microsoft's free Compatibility Pack; the file was renamed from another type; or the download finished incomplete. Since a DOCX is a ZIP underneath, a corrupted one can look like a broken archive, so try opening it in LibreOffice or Google Docs, which are more forgiving.
How do I open a DOCX without Word?
Use the free LibreOffice, Google Docs or Apple Pages. All open and edit DOCX files faithfully.
What is the difference between DOC and DOCX?
DOC is the older binary Word format. DOCX, introduced in 2007, is a smaller, open, zip-based XML format and is the current standard.
Comparisons
Related formats
Sources
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