XLSX Viewer
Open a spreadsheet without a spreadsheet program — and without uploading it.
Your spreadsheet
Read in your browserHow this reads your output
The file is parsed in the page and each sheet shown as a table, with tabs when there is more than one. The parser is fetched only once a file is chosen — it is a few hundred kilobytes, and loading it on every page of this engine would make a dozen other tools pay for it. What the viewer shows is cell values: a spreadsheet is a grid of data and a set of presentation decisions, and this reads the first. Anything it finds that will not survive a conversion to CSV — formulas, merged cells, sheets whose rows are wider than their header — is reported before you download rather than after.
What the results mean
- Formulas
- Present in the workbook and absent from a CSV, which stores the values they produced rather than the calculations.
- Merged cells
- A display decision with no CSV equivalent: the value lands in the first cell and the rest become blank.
- Uneven sheets
- Rows wider than the header row, which usually means the real header is not the first row — a title or a note sits above the table.
- Sheets
- Each is a separate table. A CSV holds one, which is why conversion produces one file per sheet.
Common problems and fixes
- The columns are shifted
- Check for merged cells in the original. A merge puts its value in the first cell and leaves the rest blank, which shifts everything after it in a naive reading.
- My numbers look different
- Values are shown as the workbook formatted them. A cell displaying £1,234.50 stores 1234.5, and rounding set by a display format is not part of the data.
- It will not open the file
- A password-protected workbook cannot be read without the password. Formats supported are xlsx, xls, ods and csv — not Numbers or Google Sheets links.
Frequently asked questions
How can I open an xlsx file without Excel?
Load it above. The file is parsed by your browser and shown as a table with a tab per sheet — no account, no upload and no spreadsheet program. It shows cell values rather than formatting, which is what you want for reading data and not for reviewing a document's layout.
Is my spreadsheet uploaded?
No. It is read by your browser using the File API and parsed in the page. This is the category where that matters most — a spreadsheet is usually the most sensitive file anyone routinely emails.
Why does the converted CSV look wrong?
Almost always merged cells or a header row that is not the first row. A merge becomes one value and some blanks, and a title above the table makes the header look like data. Both are reported above before you convert, which is the point of showing the file first.
Put this on your own site
Free to embed, no attribution required beyond the source link the frame carries itself. It runs entirely in your visitor's browser, sets no cookies and loads no third-party script.
<iframe src="https://runthetests.com/embed/xlsx-viewer/" width="100%" height="720" style="border:1px solid #e5e5e5;border-radius:8px" title="XLSX Viewer" loading="lazy"></iframe>
Preview it at https://runthetests.com/embed/xlsx-viewer/. Embedded pages are marked noindex, so yours stays the canonical copy — not this one.