01
Choose the target
Ironsheet inspects the workbook locally and shows the Excel tables it can safely update.
Free · private · browser-only
Update your Excel report without breaking the workbook.
Choose an existing Excel workbook and a fresh CSV. Ironsheet replaces the data table, validates the result, and gives you back a new copy—with the rest of your workbook intact.
Files never leave your browser
No account or installation
Original file stays untouched
XLSX and XLSM supported
Local workbook tool
Refresh an Excel table
Files stay in this browser
1
Choose your existing workbook
No workbook handy? Use our safe sample.
A narrow edit, not a rebuild
Your workbook is more than a grid of cells.
Real reports contain formulas, styles, charts, pivots, named ranges, macros, relationships, and application-specific XML. Recreating a workbook from extracted values can quietly discard those parts. Ironsheet changes the table you selected and preserves untouched package entries.
02
Match fresh data
Review the CSV headers and explicitly map every destination column before anything changes.
03
Validate and download
The updated package is checked before a temporary local download is created.
Private by architecture
No upload disguised as an upload.
The page code comes from Vercel. Your files do not go back. The browser reads them into an isolated worker, Ironsheet performs the change in memory, and the browser creates the download.
No file API route
No database
No saved result URL
No workbook analytics
Powered by the open-source engine
The demo and the library improve each other.
This tool runs through the same public browser package available to developers. The archive checks and validation-gated browser write were built for this workflow, then promoted into Ironsheet so other applications can use them too.
Built to fail safely.
The tool checks archive size before opening, refuses unsafe table expansion, validates the finished workbook, and withholds the download if structural errors are found.
Questions, answered plainly
Frequently asked questions
Does Ironsheet upload my workbook?+
No. Vercel serves this page and its code, but your workbook and CSV are read, changed, and written inside a browser worker on your device. There is no file-upload endpoint or saved result URL.
What happens when I close the tab?+
The in-memory workbook, CSV, and temporary download disappear with the browser session. The tool does not store them in a database or browser storage.
Which files work?+
This first version accepts XLSX and XLSM workbooks containing a real Excel table, plus a CSV with a header row. Legacy XLS, XLSB, encrypted workbooks, and arbitrary worksheet ranges are not supported yet.
What happens to formulas, charts, pivots, and macros?+
Ironsheet edits the targeted table inside the existing OOXML package instead of rebuilding the workbook. Untouched parts are preserved, macros are never executed, and Excel is asked to recalculate formulas when the result opens. Cached chart or pivot data may refresh in Excel.
How large can the files be?+
The current browser guardrails allow workbooks up to 25 MB compressed and CSV updates up to 50,000 rows or 250,000 cells. Actual speed depends on workbook complexity and your device.
Does this replace Excel or Google Sheets?+
No. This is a focused workbook refresh tool, not a general spreadsheet editor. It is designed for the recurring job of putting fresh exported data into an existing Excel report without recreating that report.