Quick answer: a .pub file is a document made in Microsoft Publisher, the Windows desktop-publishing app Microsoft sold from 1991 until its retirement in October 2026. It holds a page layout: text boxes, pictures and shapes at fixed positions. You can open one free in your browser with Free Pub Editor.
What is a .pub file used for?
Publisher was the go-to tool for print documents that need more layout control than Word gives: newsletters, flyers, posters, brochures, certificates, menus, programmes, calendars and business cards. Each .pub file is one publication, often several pages long, with a fixed page size such as A4, A5, Letter or a folded card.
That's why .pub files are so common in schools, churches, sports clubs and small businesses: many have years of templates saved in this format.
What's inside a .pub file?
Under the surface, a .pub file is a compound file: a single file that works like a small folder of separate data streams. Microsoft documents this container format publicly as the Compound File Binary format, which it describes as a format that "provides a file-system-like structure within a file" (Microsoft Learn). Old Word .doc and Excel .xls files use the same container.
Inside, a modern .pub file typically has:
| Stream | What it holds |
|---|---|
Contents | The publication's structure: pages, page size, the position and size of every box, colours, borders and master pages |
Quill/QuillSub/CONTENTS | The text and its formatting: fonts, sizes, paragraph spacing, tab stops, bullets. "Quill" is the name of Publisher's text engine |
Escher/EscherStm | Drawing information for shapes and pictures, in the Office drawing format Word and PowerPoint also use |
Escher/EscherDelayStm | The pictures themselves: JPEG, PNG, GIF and BMP photos, and WMF or EMF clip art |
The Office drawing format (nicknamed "Escher") is published by Microsoft as [MS-ODRAW]. Publisher's own Contents and text streams were never published, so every program that reads .pub files today relies on reverse-engineering. LibreOffice and Scribus use the open-source libmspub library; Free Pub Editor uses its own reader, written with the help of libmspub's notes.
Which versions of Publisher made .pub files?
Every version, but the format changed over time. This matters because older files are harder to open.
| Publisher version | Released | Opens in Free Pub Editor |
|---|---|---|
| Publisher 1.0 to 97 | 1991 to 1996 | Not yet |
| Publisher 2000 | 1999 | Text only, page by page |
| Publisher 2002 and 2003 | 2001, 2003 | Yes, with layout |
| Publisher 2007, 2010, 2013, 2016 | 2007 to 2015 | Yes, with layout |
| Publisher 2019, 2021, Microsoft 365 | 2018 to 2026 | Yes, with layout |
We haven't tested Publisher 98 files yet. Release years from Wikipedia's Publisher article.
How do I open a .pub file?
- Go to freepubeditor.com/editor in Chrome, Edge, Safari or Firefox.
- Click Open and choose the .pub file. It's read in your browser, not uploaded.
- Edit, print, or click Export PDF to save a copy anyone can open.
Other ways to open .pub files are compared in how to open a .pub file online. On a Mac, see opening .pub files on a Mac.
How is a .pub file different from other formats?
| Format | Made by | Editable? | Layout |
|---|---|---|---|
| .pub | Microsoft Publisher | Yes | Fixed boxes on a page |
| Almost anything | Not really | Fixed, final copy | |
| .docx | Microsoft Word | Yes | Text flows down the page |
| .afpub | Affinity Publisher | Yes | Fixed boxes; a different format from .pub |