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Is it possible to view the source code of the XLL Excel add in without having the original source code? I'm guessing that this XLL was written in C#, but not sure. I.e. a .NET DLL you can decompile with dotPeek, or an XLA file you can open in Excel via Developer > Visual Basic. I tried both approaches with no luck.

Hoppe
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  • Have you searched for the source code? [Excell XLL Add-In Library Source Code](https://xll.codeplex.com/SourceControl/latest). It's C++, by the way. – Tim Jun 30 '15 at 17:01
  • Now I have :) but didn't find anything :( @Tim – Hoppe Jun 30 '15 at 17:38

2 Answers2

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Do you know if this Excel Add-In was built using Excel-DNA? If it was, then you can extract the .NET assemblies from the .XLL file using ExcelDnaUnpack.

Source code is on GitHub: https://github.com/augustoproiete/ExcelDnaUnpack

You can download ExcelDnaUnpack.exe (the compiled tool ready to use) in the Releases tab of the project on GitHub.

ExcelDnaUnpack is a command-line utility to extract the contents of ExcelDna add-ins packed with ExcelDnaPack

Usage: ExcelDnaUnpack.exe [<options>]

Where [<options>] is any of:

--xllFile=VALUE    The XLL file to be unpacked; e.g. MyAddIn-packed.xll
--outFolder=VALUE  [Optional] The folder into which the extracted files will be written; defaults to '.\unpacked'
--overwrite        [Optional] Allow existing files of the same name to be overwritten

Example: ExcelDnaUnpack.exe --xllFile=MyAddins\FirstAddin-packed.xll
         The extracted files will be saved to MyAddins\unpacked
C. Augusto Proiete
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As a general answer, XLL are written using the Excel C Api, they are in reality standards dlls. When you create a xll, you basically create a dll and rename the extension to turn it in a .xll. So your question in fact resume to this question : How to decompile c++ dll?

Community
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Malick
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