Spreadsheet tools in the browser
What stays local
The Excel studio compares workbooks, merges sheets, splits a workbook, drops empty rows, protects a sheet, and converts CSV or PDF. The workbook is read in the browser. NexTool does not upload it. CSV and Excel to PDF are separate addresses so you can open the job directly. CSV from the sample inventory workbook should be one file, not a ZIP, because that workbook has a single Inventory sheet. PDF export draws the preview of that sheet. It does not add a title the sheet did not have.
Optional AI formulas are the exception. A formula request goes to the API address in Settings. The key stays in this browser. NexTool does not receive it. The spreadsheet file itself is still read locally for the headers you send with that request. Do not turn AI on for a workbook you are not willing to describe to that provider. Ordinary compare, CSV, and PDF export do not use the API. Check numbers after any conversion. A protected sheet or a dropped empty row can change what a later formula sees.