XLSB

XLSB (Excel Binary) is one of the formats that Excel spreadsheets can be saved under. It was introduced at the same time as the more common XLSX format which replaced the older XLS. XLS was a pure binary format, while XLSX is XML-based and its files are actually ZIP archives containing a number of sub-files related to the spreadsheet. XLSB is similar, in that it is actually a ZIP file (even though the extension is not .zip), but the main files within the ZIP are binary files with a .bin extension. There are also some other files within the ZIP including images and even some XML files, but the main content is in the binary files.

Format information

 * [MS-XLSB : Excel (.xlsb) Binary File Format]
 * Office 2007 .bin file format
 * Cracking the Office 2007 .bin file format

Sample files

 * 2048 Game for Excel is distributed in this format.

Other links

 * New binary format for spreadsheets
 * Excel 2007 Binary File Format (.xlsb) as a timesaver
 * Library of Congress Sustainability of Digital Formats XLSB description
 * ForensicsWiki entry (minimal info)