In-browser workbook check

See what openpyxl removes from your workbook

Drop an Excel workbook. This page runs openpyxl 3.1.5 in your browser, makes the one-cell edit from our agent-edit study, saves, and lists what did not survive. The file never leaves your device.

Check a workbook

Each file gets the study's edit: load with openpyxl (keeping VBA for .xlsm), set Z1 on the first sheet to =1+1, and save. The page then compares the saved copy with your original. Your original file is not changed.

Drop .xlsx or .xlsm workbooks hereor choose files. They are read by this tab and never uploaded.

Python loads only after you choose a file. The first check downloads Pyodide 0.29.5 and openpyxl 3.1.5 (about 6 MB); later checks in this tab reuse them.

What the check measures

Package parts removed: every zip part in the original that is absent after the save. xl/calcChain.xml is not counted because Excel rebuilds it.
Feature families lost: fewer primary parts for VBA, pivot tables and caches, charts, slicers, timelines, external links, drawings, tables, comments, or a Power Pivot model.
Sheet extension features: x14 extension elements, conditional formatting blocks, and data validation rules across all worksheets, plus a digest of the x14 content so a changed extension is not mistaken for an intact one.
openpyxl warnings: the messages openpyxl raised while loading and saving, such as an extension it does not support and will remove.

This is the edit step only. An agent workflow that then recalculates the file through LibreOffice can remove more; the study measures both steps. The comparison code is the study harness's, and the public harness reruns the full method, recalculation included, on your machine.

Where your workbook goes

Your browser reads the file and hands its bytes to a background worker in this tab.
The worker writes it to an in-memory filesystem, runs openpyxl there, and deletes both copies when the check finishes. Nothing is uploaded or stored.
The only downloads come from this site: the unmodified Pyodide 0.29.5 runtime (MPL-2.0) and copies of the PyPI files openpyxl-3.1.5-py2.py3-none-any.whl and et_xmlfile-2.0.0-py3-none-any.whl, each checked against its pinned SHA-256 before it is installed. None of these requests carries workbook data.
The site's cookieless analytics counts the visit, as on every page. It records no file name, content, or result.

Make the same edit without the losses

WolfXL Community is MIT-licensed, on PyPI, and includes modify mode, which patches the cells you change and copies every other package part through unchanged. Read the modify mode documentation or the study write-up.

pip install wolfxl

import wolfxl

wb = wolfxl.load_workbook("report.xlsx", modify=True)  # keep_vba=True for .xlsm
wb[wb.sheetnames[0]]["Z1"] = "=1+1"
wb.save("report.xlsx")