What is the EBK file format?
An .ebk file contains an ebook created with the eBook Pro publishing tool, developed by The Internet Marketing Center. .ebk files use compression and encryption: source content is authored as HTML, then compiled, compressed, and encrypted into a single proprietary binary container. To open an .ebk ebook a reader must supply valid login credentials and use the free eBook Pro Viewer - the only application that can decrypt and display the content.
eBook Pro was a handy tool for authors who self-distributed their books. A generated .ebk file remains secured even if it has been copied many times; without valid credentials, no reader can access the content. The author had access to book sales data and information about their readers through the eBook Pro platform.
The format is now obsolete, tied to discontinued software no longer in active development. Opening legacy .ebk files still requires the original eBook Pro Viewer, which runs on Windows only. Modern self-publishing has largely moved to open standards such as EPUB and MOBI for wider reader compatibility.
Security & safety
RISK: MEDIUMThe file is passive ebook data, but the real issue is access and provenance: legacy .ebk files are DRM-encrypted and orphaned, and searches for "ebk reader/opener" lead to low-quality or PUP-bundled download sites. Avoid sketchy "universal ebk viewer" downloads. Confirm whether a given .ebk is actually an Outlook Express Backup Genie mail backup before trying ebook tools.
Format details
in a nutshell- Mobipocket / eReader ebook (EBK) - Some ebook readers used .ebk for Mobipocket-style or eReader titles.
- EBookME mobile ebook - .ebk ebooks generated by EBookME for early Java/mobile e-reading.
- Outlook Express Backup Genie backup - Mailbox backup created by Outlook Express Backup Genie (the DB's original db_name).
Programs that open EBK files
Windows1 app
eBook Pro Viewer
Free Open the .ebk in the original eBook Pro viewer with the required permission/key; no modern alternative exists. Technical details
deep spec| Container | Proprietary eBook Pro binary container (single-file compilation of all ebook content and assets) |
| Encoding | Binary; no plain-text representation |
| Source format | HTML - pages must be authored in HTML before compilation by eBook Pro |
| Compression | Content and embedded assets are compressed prior to encryption |
| Encryption | Proprietary encryption applied after compression; file can only be decrypted by the eBook Pro Viewer |
| File signature (magic bytes) | No documented constant signature; file is identified by origin rather than a fixed byte sequence |
| MIME type | application/octet-stream |
| DRM model | Credential-based lock; the ebook is inaccessible without a valid user login supplied to the viewer |
| Embedded assets | HTML pages, inline images, and supporting assets compiled into one container |
| Platform | Windows only - eBook Pro Viewer has no macOS or Linux release |
| Typical file size | Hundreds of KB to a few MB per title |
| Associated software | eBook Pro Viewer (free, Windows-only; required to open .ebk files) |
| Format status | Obsolete; tied to discontinued eBook Pro software; superseded by EPUB and MOBI/AZW for modern distribution |
| Released | late 1990s - early 2000s (eBook Pro publishing software) |
EBK conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about EBK files.
