I use a program called Beyond Compare for synchronizing various backups and folders and I’ve noticed that SharePoint [2010] (at least for the newer versions of Excel and Powerpoint) seems to unzip and rezip these hybrid files that Microsoft uses now (.xlsx and .pptx). These files are actually zipped XML files - if you have a binary editor or simply rename a .xlsx or .pptx file to .zip you’ll see that’s how they are stored now. Anyway, the long and short of it is that when I upload to SharePoint an Excel or PowerPoint file (not sure if it happens to .docx files too yet) SharePoint unzips and rezips the contents making the files no longer identical (at least from a binary data value standpoint).

I am wondering whether the ‘new’ version of SharePoint [2013] has this ‘feature’ too.

Asking for a friend.

(SP version numbers added in brackets by me.)

What's going on here? Is SharePoint really repackaging the Office docs? Or is it an effect of the files moving into and out of content DBs?

  • I can't reproduce this with a simple Word doc when going into a SharePoint 2016 ODfB site, re-downloading it, and comparing with the original. MD5 sum is identical.
    – user6024
    Oct 5, 2017 at 15:37

1 Answer 1


This is likely partly due to being a BLOB in a content database, and maybe also to do with metadata - native or extended - in the document library.

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