File Formats: Microsoft Excel Spreadsheet (XLSX/XLS/XLSB)

The XLSX, XLS, and XLSB file extensions are used for Microsoft Excel spreadsheets, part of the Microsoft Office Suite of software.

XLSX/XLS files are used to store and manage data such as numbers, formulas, text, and drawing shapes.

XLSX is part of Microsoft Office Open XML specification (also known as OOXML or OpenXML), and was introduced with Office 2007. XLSX is a zipped, XML-based file format. Microsoft Excel 2007 and later uses XLSX as the default file format when creating a new spreadsheet. Support for loading and saving legacy XLS files is also included.

XLS is the default format used with Office 97-2003. XLS is a Microsoft proprietary Binary Interchange File Format. Microsoft Excel 97-2003 uses XLS as the default file format when creating a new document.

XLSB is the Excel Binary File Format, a macro enabled spreadsheet.

Note: XLSX, XLS, and XSLB file formats are supported in the Document/Medical products.


LEADTOOLS supports all flavors of the Microsoft Excel spreadsheet format, from Office 97 XLS up to XLSX.

LEADTOOLS uses the XLSX filter to load XLSX files.

LEADTOOLS uses the XLS filter to load XLS files.

Additional features supported by LEADTOOLS:

The default extension used by this format is: XLSX or XLS.

The CodecsExcelOptions Class provides options for loading XLS/XLSX files.

File Constants

The file constants associated with this file format are:

Constant Read Support Write Support Description
Xlsx, Xlsb 24 BPP N/A XLSX, Microsoft Excel spreadsheet file format
Xls 24 BPP See Using Document Writers XLS, Microsoft Excel 97-2003 spreadsheet file format

Required DLL: Leadtools.Codecs.Xlx.dll or Leadtools.Codecs.Xls.dll. The XLSX file format requires .NET Framework 4.0 or later, as well as the DocumentFormat.OpenXml.dll (ver. 2.0). For a listing of the exact DLLs needed, based on the toolkit version, refer to XLS, XLSB Format Support and XLSX Format Support

Platform Support

Extension Module Value Win32 Win64 Net32 Net64 Linux Android Apple UWP MimeType Friendly Name
Xls XLS 341 application/ XLS - Microsoft Excel 97-2003 File Format
Xlsx XLSX 351 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet XLSX - Microsoft Office Excel File Format
Xlsb XLSX 403 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet XLSB - Excel Binary File Format

For a complete list for supported file formats, see Summary of All Supported File Formats.

For details of the file formats supported across products and platforms, refer to File Format Comparison Chart.

Using Document Writers

LEADTOOLS supports writing the XLS file format using the LEADTOOLS Document Writers. For more information, refer to LEADTOOLS Document Writers SDK.

For additional support details, refer to the following topics:

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