Which spreadsheet formulas are supported?

Standard mathematical operators (+, -, *, /), as well as core aggregation functions like SUM, AVERAGE, MIN, MAX, and COUNT over ranges (e.g., =SUM(A1:A20)).

Can I export back to real Excel .xlsx files?

Yes. One click exports a genuine Microsoft Excel .xlsx workbook with multiple sheets and formulas intact.

Is there a file size limit?

There is no artificial limit. Spreadsheets with tens of thousands of cells are processed smoothly on standard computers.

In-Browser Excel & Spreadsheet Editor

Spreadsheet100% In-Browser

Open, edit, and calculate XLSX, XLS, and CSV spreadsheets locally. Supports formulas (SUM, AVERAGE), multi-sheet tabs, and instant export.

or open local file:

Open .XLSX, .XLS, or .CSV

100%

Font:

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Sheets (1):

Zero Data Collection

Files are processed 100% locally

Instant Client-Side Speed

Zero network upload delays

Free & Unlimited

No registration or credit card needed

Free In-Browser Excel & Spreadsheet Editor — No Cloud Uploads

Why we built this: Microsoft 365 and Google Sheets require logins, cloud file uploads, and continuous internet connectivity. When you simply need to view, tweak, or calculate numbers on confidential client spreadsheets, cloud uploads pose compliance and privacy risks. This editor runs 100% on-device.

How it works: 1) Open any .xlsx, .xls, or .csv spreadsheet (or create a blank one). 2) Navigate multi-sheet tabs, edit cells with full keyboard support (Tab, Enter, arrows), add or delete rows and columns, and sort data. 3) Write mathematical formulas like =SUM(A1:A10) or =AVERAGE(B1:B5), and export your updated sheet as .xlsx or .csv instantly.

Powered by SheetJS compiled for modern browsers, the spreadsheet engine decodes workbook binary streams directly into JavaScript memory arrays, computing cell values without server roundtrips.

Frequently Asked Questions

Everything you need to know about using In-Browser Excel & Spreadsheet Editor safely and efficiently.

No. The spreadsheet is parsed, edited, and re-saved entirely in your browser memory. You can even use this tool completely offline.

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