What Is an XLL File?
A file with the XLLfile extensionis an Excel Add-in file.
Excel Add-in files are similar toDLLfiles except that they’re built specifically for Excel.
XLL Files.
How to Open an XLL File
XLL files can be opened withMicrosoft Excel.
Select theAdd-inscategory and then chooseExcel Add-insin theManagedrop-down box.
ChooseGoand thenBrowseto locate it.
XLAM files are just XLA files that can contain macros.
They also differ from XLA in that they useXMLandZIPto compress data.
To start, XLA/XLAM files are written in VBA while XLL files are written in C or C++.
You’ll find lots of detailed instructions fromAdd-In-Express.
Still Can’t Open It?
For example, an XL file is also an Excel file, but it’s used as a spreadsheet.
They also open with Excel, but not through the method described above for XLL files.
They instead are used likeXLSXandXLSfiles.
