Document format
What is a .docx file?
DOCX is the document format of Microsoft Word since 2007. It keeps text, styles, tables and images in a form anyone with a word processor can keep editing.
Inside, a DOCX is a ZIP full of XML files. Word, LibreOffice, Google Docs and Pages all open it, though complex layouts can shift from one to another.
fileclay opens and writes DOCX
DOCX vs ODT vs PDF
| DOCX | ODT | ||
|---|---|---|---|
| Editing | Easy | Easy | Difficult |
| Layout | Flows with editing | Flows with editing | Fixed |
| Default in | Microsoft Word | LibreOffice | Readers, browsers |
| Opens in browsers | No | No | Yes |
| Best for | Drafts, collaboration | Open-source workflows | Final documents |
When to use DOCX
Good for
- Documents that will still change
- Reports and letters shared with Word users
- Templates with styles
Not a good fit
- Final versions that must look exact: use PDF
- Long-term archives: PDF/A is safer
- Reading on a phone without Word or a similar app
How to open .docx files
| Platform | App | Notes |
|---|---|---|
| Windows, macOS | Microsoft Word | Full support |
| Any system | LibreOffice Writer | Free; complex layouts may shift |
| macOS, iPhone | Pages | Built in; opens and exports |
| Browsers | Word for the web, Google Docs | Needs an account |
| Android, iPhone | Microsoft Word | Free app |
Convert DOCX files
How to identify a .docx file
A DOCX is a ZIP, so it starts with “PK”, like XLSX, ODT and EPUB. What tells them apart is the list of files inside.
It’s read here, in your browser. Only the first bytes.
Your file
What comes after
Questions about DOCX
What is the difference between DOC and DOCX?
DOC is the old binary format, and DOCX is the XML-based one Word has used since 2007. DOCX files are smaller and easier to recover.
Can I open a DOCX without Word?
Yes. LibreOffice, Google Docs and Pages all open it, for free.
Why does my DOCX look different in another app?
Each program lays out text in its own way, and fonts may be missing. PDF is the format that keeps the layout.
Can a DOCX contain viruses?
A .docx can’t contain macros, which are the classic risk. Those go in .docm. Be careful with attachments anyway.
Can I see what is inside a DOCX?
Yes. Rename a copy to .zip and open it: the text is in word/document.xml.