What is a PUB file?
A .pub file is a document made with Microsoft Publisher, the desktop publishing app of Microsoft Office: typically a newsletter, flyer, brochure, card, certificate or poster. It holds the text, the pictures and the page layout together in one file.
Updated on 27 October 2026.
Why a PUB file may not open any more
Only Publisher can open a .pub file with its exact layout, and Publisher is being retired. According to Microsoft, Microsoft 365 subscribers lose access to Publisher "on or shortly after October 1, 2026", and support for the perpetual version (Office 2021 and LTSC 2021) ends on October 13, 2026 (Microsoft Support). Word, PowerPoint and the other Microsoft 365 apps do not open .pub files. Microsoft's advice is to convert them: to PDF to view them, or to PDF then Word to edit them.
What is inside a .pub file
We opened 21 sample .pub files from the public test suite of the Apache POI project, saved by Publisher 98, 2000 and 2010. All of them share the same structure:
- A container, not a single document. A .pub file is an OLE compound file, the same "file system in a file" used by old .doc and .xls files. It starts with the bytes
D0 CF 11 E0 A1 B1 1A E1. - The text sits in a stream called
Quill/QuillSub/CONTENTS, stored as Unicode (UTF-16), story by story. - The pictures and shapes sit in
Escherstreams. Photos are kept as ordinary JPEG or PNG data, at their original resolution. Clip art and drawings are often WMF or EMF vector files. - The layout (pages, frames, positions, fonts, colours) lives in the
Contentsstream, in a format Microsoft never documented publicly. That is why other programs only approximate it. - A small picture of page 1 (about 100 × 145 pixels) is saved in the document properties, so file managers can show a thumbnail.
So even without Publisher, the words and the embedded JPEG/PNG photos of a .pub file can usually be extracted. Only the page design is hard to rebuild.
How to open a PUB file today
- In your browser: the free PUB file viewer on this site reads the file on your own device (nothing is uploaded) and shows the page 1 preview, all the text and all the photos.
- With LibreOffice Draw (free desktop app), which imports the layout approximately.
- With an old copy of Publisher, if you still have one: open the file and save it as PDF.
Details and pros and cons of each method: how to open a PUB file. To keep a copy that opens everywhere: PUB to PDF or PUB to Word.
Quick answers
Is a .pub file a virus?
No, it is a normal document format. As with any document from an unknown sender, be careful with files you did not expect.
Can I open a .pub file on a Mac or a Chromebook?
Publisher never existed for Mac or ChromeOS. A browser-based viewer needs nothing to install (this one has been tested so far in Chromium-based desktop browsers: Chrome, Edge), and LibreOffice runs on Mac.
Can Word open a .pub file?
No. Word cannot open .pub files. Convert the file first, then open the result in Word.
Is every .pub file a Publisher file?
Almost always on Windows. A few other programs use the .pub extension (for example some SSH public keys are named id_rsa.pub); those are plain text files and are not Publisher documents.