RunLocalTools

Spreadsheet Viewer

Open XLSX, XLS, XLSB, ODS, CSV, TSV, and DBF files — browse the data right here, nothing leaves your browser. Not everyone has Excel installed, and not every situation calls for opening a full desktop application just to check what’s inside a spreadsheet someone sent you. The XLSX Viewer opens .xlsx and .xls files directly in the browser — multiple sheets, formulas shown as their calculated values, basic formatting preserved — so you can look at the data without installing anything or waiting for a heavyweight application to launch.

Why local processing matters here

Spreadsheets carry some of the most sensitive data that regularly gets shared as a file — payroll, customer lists, sales figures, financial statements, HR records. A server-side viewer means that file, and everything in it, gets uploaded somewhere before you even get to look at it, which is a real exposure for a file you might only need to glance at once. Everything here parses and renders in your browser; the file never leaves your machine to be viewed.

How to use it

  1. Upload your .xlsx or .xls file — drag and drop or use the file picker, whichever’s faster.
  2. Switch between sheets using the tabs at the bottom, the same way you would in a desktop spreadsheet app.
  3. Formulas display as their calculated result by default; toggle to formula view if you need to see the underlying formula text rather than just the output.
  4. Use the search function to find a specific value or text string across the whole workbook rather than scanning sheet by sheet.
  5. Sort or filter a column temporarily within the viewer if you’re trying to scan for specific rows, without altering the underlying file.
  6. If you need to extract just part of the data, select and copy the relevant cells directly — the viewer supports normal copy behavior so the data can be pasted elsewhere.

Common situations this solves

  • Quickly checking the contents of a spreadsheet someone emailed you, without installing Excel or waiting for a desktop app to open.
  • Viewing an .xlsx file on a device (like a phone or a locked-down work machine) where installing spreadsheet software isn’t an option.
  • Confirming which sheet or tab contains the data you actually need before deciding whether to download or process the full file further.
  • Checking formula logic in a shared financial model without accidentally triggering a recalculation or edit in the original file.
  • Verifying that a spreadsheet exported from another system (an accounting tool, a CRM) looks correct before importing it somewhere else.

FAQ

Why do some cells show different values than I expect? This is often a formatting issue rather than a data issue — a date stored as a number, or a percentage stored as a decimal, can display differently depending on how the cell’s format is being interpreted. Check the raw cell value against its displayed format if a number looks unexpected.

Does this support older .xls files, or only the newer .xlsx format? Both are supported — .xls (the older binary format) and .xlsx (the newer XML-based format introduced with Excel 2007) open the same way in the viewer, though very old or unusual .xls variants occasionally have formatting quirks that don’t translate perfectly.

Can I edit the spreadsheet in this viewer, or is it view-only? It’s built primarily for viewing — you can copy data out, but it’s not intended as a full editing replacement for Excel or Google Sheets. For substantial edits, downloading and opening in a proper spreadsheet application is still the better tool for the job.

Why don’t my charts or embedded images show up? Chart and image rendering support varies depending on complexity — basic charts typically render, but more advanced chart types or heavily customized formatting may not display exactly as they would in Excel itself, since the viewer prioritizes accurate data display over full visual fidelity.

Does this handle password-protected spreadsheet files? No — password-protected or encrypted .xlsx files need to be unlocked in a full spreadsheet application first, since the viewer doesn’t include decryption support.

Can I view multiple large sheets without the browser slowing down? Performance depends on file size and complexity — for most everyday spreadsheets this isn’t an issue, but a workbook with tens of thousands of rows across many sheets and heavy formula use may render more slowly than a smaller file, since everything is being processed by your browser rather than a dedicated application.

If what you actually need is to combine data from more than one spreadsheet or CSV rather than just view one, Merge CSVs handles that next step, and CSV cleaner is worth a look if the data itself needs tidying up before it’s usable.