Free CSV to XLSX Converter: No Sign-up, Nothing Uploaded
This free CSV to XLSX converter wraps comma-separated text in an Excel workbook. There is no sign-up or login, no watermark, and no upload: your data stays in your browser and never leaves your device.
A CSV file opens as plain text in many places, and Excel can mangle it when you double-click. Converting to XLSX gives you a proper workbook with the rows and columns in place, ready to edit, filter and save.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Drag your CSV files onto the page or choose them with the file picker.
- Pick XLSX as the target format.
- Adjust any options shown, then start the conversion.
- Download each workbook, or take a batch as one ZIP.
Features
- Runs natively in your browser with no engine download.
- Each CSV becomes one sheet in a new workbook.
- Convert many files in one batch.
- No watermark and no account.
- The result opens in Excel and other spreadsheet apps.
Supported formats
| Format | Read | Write | Notes |
|---|---|---|---|
| CSV.csv | Yes | Yes | Comma-separated values: one row per line, plain text with no formatting. |
| Excel (XLSX).xlsx | Yes | Yes | The default Excel format since 2007. |
About the formats
CSV versus XLSX
CSV is plain text with one row per line and no formatting, so it opens everywhere. XLSX is a ZIP of XML files that supports several sheets, formulas and charts. Converting gains the container, not new content: the workbook holds the same values the CSV did.
You can add formulas, formatting and charts afterwards in your spreadsheet app.
Privacy: how it works
- Your CSV files stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
- Exports from CRMs and accounting tools often contain personal data. Nothing is sent to a server, so that data is not exposed by converting it here.
Tips
- Make sure the first row holds your column headers before converting.
- If values were split into the wrong columns, the file may use semicolons or tabs, so try converting it as TSV instead.
- Check long ID numbers after opening, since spreadsheet apps may show them in scientific notation.
- Keep the original CSV as the plain-text source of truth for imports.
- Convert files one at a time if a very large CSV strains your browser.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your CSV files are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow, and a very big batch may need to be split into smaller runs.
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