EPUB File Extension
Open EBook Format
- File Type epub
- Developer IDPF
- Popularity
- Application Sigil
- Category eBook Files
- Format Zip
What is a EPUB file?
The EPUB file extension is linked to Open EBook Format and belongs to the eBook Files category, which includes 74 files.
EPUB file support extends to various operating systems, including Windows, Mac OS and Linux, as well as mobile devices running Apple iOS, Windows Phone and Android. When working with EPUB files, you can rely on 28 programs, including FBReader, iBooks and Stanza.
File Signature
HEX code: 50 4B 03 04. ASCII code: PK.
Programs that support EPUB files
Windows
Mac OS
Windows Phone
Online Services
How to open a EPUB file?
If you can’t open a EPUB file, it is usually because the necessary software is missing. To resolve the issue, select the right program from the list for your operating system. Then go to the official website of the developer, download the software, and install it.
When it comes to opening and working with EPUB files, FBReader, iBooks and Stanza are the top choices for users. If you need the newest version of Sigil, just access the website. From there you can download the installer compatible with all systems.
After successful installation, your operating system should seamlessly handle EPUB files via Sigil.
Set Sigil as your default EPUB viewer
Changing Default Programs in Windows
- Right-click on your EPUB file, then choose the "Open with" option and select "Choose another application" from the available options;
- From the list of applications in the pop-up window, find and select Sigil as your desired application;
- Check the "Always use this app" checkbox, and then click "OK" to set your chosen app as the default for opening EPUB files.
Set default app to open files on Mac
- Right-click or Control + left-click on the desired EPUB file to open a menu of available actions;
- Select "Open in application" and click "Other";
- Go to the lower section of the window, where you will find the "Enable" menu. By default, it is set to "Recommended Programs";
- Select "All Programs" from this menu and proceed to search for Sigil. Check the box next to "Always open in app" to set it as the default option.
Solving Common EPUB File Challenges
EPUB files may present some challenges, but most can be easily addressed with minor software tweaks. See the troubleshooting tips below for guidance.
What can lead to sudden Sigil crashes?
Sigil crashes can be caused by outdated software. Keep your developer products up to date by installing the latest updates.
A simple restart of your computer can often fix many common problems, which is why it is the recommended first step before making any adjustments to your software settings.
What is the recommended approach to repair a damaged EPUB file?
Use a data recovery program to open the damaged EPUB file and from the menu choose "Repair" function to start the repair process. Then wait for the recovery process to complete, which allows you to automatically repair corrupted ebook files.
What are the warning signs that my EPUB file may be corrupted?
Common indications of damaged EPUB ebook files are:
- Error messages appear during the course of working with the file;
- Editing the archive in QuarkXPress results in slow or unresponsive behavior;
- The file does not open or opens with errors;
- Unexplained increase in EPUB file size;
- File hangs or crashes in Sigil or other programs;
How to edit a EPUB file?
To edit EPUB files, it is essential to install software that supports not only viewing but also editing the ebook files. Online EPUB editors provide limited functionality compared to full-featured software for Open EBook Format.
Best EPUB editors in 2026
With the mentioned criteria in mind, we have assembled a selection of EPUB editors.
| EPUB Editor Software | Developer | Platforms | Overall Rating |
|---|---|---|---|
| QuarkXPress | Quark | Windows, Mac OS | 4.9 out of 5 (38 reviews) |
| Adobe InDesign | Adobe | Windows, Mac OS | 4.7 out of 5 (42 reviews) |
| eCub | Julian Smart | Windows, Mac OS, Linux | 4.6 out of 5 (37 reviews) |
| Sigil | - | Windows, Mac OS | 4.5 out of 5 (40 reviews) |
Convert to and from EPUB
If handling a EPUB file is problematic, consider converting it to alternative formats such as WAV, MP3, WMA, OGG, PDF or other supported types.
Keep in mind that converting a EPUB file may introduce some limitations, but the original format can often be restored.
With applications like Calibre, Hamster Free eBook Converter and Epubor Ultimate Converter, you can convert EPUB files offline while keeping the original quality intact.