xlsx

Use openpyxl to write formulas as strings, such as sheet['B10'] = '=SUM(B2:B9)', rather than hardcoding computed values. After saving, run scripts/recalc.py so LibreOffice calculates every formula and caches the values, since openpyxl alone writes no cached results.

Use pandas read_excel for bulk data in or out, and openpyxl when you need formulas, formatting, or cell-level edits. For a quick look at sheet contents, the markitdown command renders each sheet without cell coordinates.

LibreOffice implements fewer functions than Excel, so post-2007 functions like TEXTJOIN or IFS need an _xlfn. prefix when written by openpyxl. Functions like XLOOKUP, FILTER, and UNIQUE cannot be evaluated at all and must be replaced with INDEX/MATCH or Python-side processing.

Only if you pass keep_vba=True to load_workbook. Without that flag, saving an .xlsm file through openpyxl strips all macros permanently.

openpyxl writes formulas without cached values, so data_only=True reads None until the file is recalculated. Run scripts/recalc.py first, and never save a workbook loaded with data_only=True because it replaces every formula with a literal.

Do not use it when the primary deliverable is a Word document, HTML report, standalone Python script, database pipeline, or Google Sheets API integration. It applies only when the final deliverable is an actual spreadsheet file.