Clean an Excel file before sharing CLEANSHEET

The five things a spreadsheet keeps that you cannot see

• Hidden and very hidden sheets. A sheet hidden in Excel is one right-click from visible. A sheet set to VeryHidden does not appear in the unhide list at all and can only be revealed through the VBA editor, which is exactly why people use it, and why a recipient who knows will look.
• The pivot cache. This is the one that catches people. A PivotTable stores its own copy of the source rows inside the file. Delete the sheet the pivot was built from and the pivot still works, because the data is still there: the whole original table, readable by anything that opens the archive.
• Formulas. A cell showing a number may be a formula reaching into a sheet you removed, a workbook on a network share, or a calculation whose logic is the commercially sensitive part. Freezing them to their values keeps what you meant to send.
• External links and paths. A link to \\fileserver\finance\2026\model-v4.xlsx names your server, your department structure and your file naming, and travels in the file whether or not the link still resolves.
• Comments, notes and the document properties: author, company, template, last saved by, total editing time.

What it does not do

It does not change what is in the cells you can see. A column of customer names stays a column of customer names; removing hidden data is not the same as removing data. For finding the personal columns in an export, DATASCAN points at them and ANON pseudonymises them.

It also does not repair a corrupt workbook, and it will not preserve a macro: a cleaned file is a data file. If the macros are the point, this is the wrong tool.

Checking it

An .xlsx is a zip. Rename a copy, open it, and look: the sheets are in xl/worksheets/, the pivot caches in xl/pivotCache/, the properties in docProps/. If pivotCache is gone and docProps/core.xml is empty of names, it did what it says. What a spreadsheet still contains goes through the whole list with the reasons.