> ## Documentation Index > Fetch the complete documentation index at: https://docs.dume.ai/llms.txt > Use this file to discover all available pages before exploring further. # Dume Sheets > A native .xlsx spreadsheet editor in Cowork desktop with Dume's AI copilot built in. Part of [Dume Office](/office/overview), currently in **beta**. Dume Sheets is a native `.xlsx` spreadsheet editor in Cowork desktop. It opens and saves real Excel files on your machine, and Dume's AI copilot is built into the editor itself. ## Opening a sheet * **Ask in chat**: "Build a spreadsheet to track Q4 hiring" opens Dume Sheets with a starting structure. * **New File** inside Dume Office for a blank spreadsheet. * **Open an existing `.xlsx`** from Cowork; it launches in Dume Sheets already editable. See [Dume Office](/office/overview) for all three entry points in detail. ## What the copilot can do Because the copilot has the spreadsheet open, it can do anything you'd otherwise do by hand: build out a new sheet from a description, clean up messy data, add or fix formulas, restructure columns, or explain what a sheet is doing before you rely on it. Point it at a specific tab or range rather than the whole workbook for a tighter result. ``` Build a spreadsheet to track Q4 hiring: Role, Owner, Status, Start date Clean up column C, the dates are inconsistently formatted Add a formula in D that totals column C Explain what this sheet is calculating Restructure this so each region has its own tab ``` ## Google Sheets vs. Dume Sheets Dume Sheets edits a local `.xlsx` file. If you instead want Dume to edit a spreadsheet that lives in Google Drive without ever downloading it, use the [Google Sheets integration](/integrations/google_sheets). To move a Google Sheet into Dume Sheets, download it, edit it locally, then push it back to Drive when you're done; see [Working with Google Drive files](/office/overview#working-with-google-drive-files).