What is a XLK file?
A .XLK file is a Microsoft Excel Backup File generated by Microsoft Excel. When you activate the "Always create backup" option during saving, the software automatically creates a duplicate of your spreadsheet. Internally, a .XLK file contains the exact same data structure as the original spreadsheet. Depending on the software version, the internal format might be a modern ZIP-based archive (like .XLSX) or a legacy compound document (like .XLS).
How to open XLK files?
The most direct way to open a .XLK file is with Microsoft Excel on Windows or macOS. If you do not have this software installed, you can use free, open-source spreadsheet applications such as LibreOffice Calc or Apache OpenOffice Calc. Alternatively, because the internal structure matches standard spreadsheets, you can often rename the .XLK extension to .XLS or .XLSX and open the file normally.
Best practices and troubleshooting
Because a .XLK file can represent multiple generations of spreadsheet formats, viewer.online/xlk analyzes .XLK files to identify their exact format and creator software. It shows which programs can open the file, and usually previews it. If your system does not recognize the file, we recommend using viewer.online/xlk to identify the actual format of your file before manually renaming or modifying it.
Software and tools
Beyond local spreadsheet software, you can convert these backups into standard formats for easier sharing. We recommend file conversion to sensible target formats on convert.guru. Using this service, you can convert .XLK files directly to .XLSX, .CSV, or .PDF.
Summary
viewer.online/xlk directly opens and previews .XLK files in the browser, eliminating the need to install software or troubleshoot compatibility issues.