Convert XLSX to CSV Online Free — No Upload, Data Intact
Turn .xlsx workbooks into clean UTF-8 CSV files right in your browser — with BOM so Excel opens them without garbled characters. No upload, no signup, no limits.
Drop .xlsx, .xlsm, or .xls files here, or click to browse
Supports .xlsx / .xlsm / .xls · processed locally · never uploaded
How to Convert Excel to CSV Online
- Drop one or more .xlsx, .xlsm, or .xls files — everything is processed locally and never uploaded.
- Click Convert to CSV — each worksheet is exported as a separate CSV with proper escaping.
- Check the report — every file lists its sheet count, total rows, and column count.
- Download the result — a single-sheet workbook gives you one CSV; multi-sheet workbooks are zipped together.
How It Works (and Why Excel Opens the CSV Correctly)
Your workbook is parsed in the browser with SheetJS, the same open-source library used by many spreadsheet tools. Each worksheet is serialized to CSV following RFC 4180: fields containing commas, quotes, or line breaks are wrapped in double quotes, and embedded quotes are doubled. Rows are separated by CRLF, the line ending Excel expects.
Every CSV starts with a UTF-8 BOM (byte order mark). Without it, Excel on Windows guesses the encoding and often picks a legacy code page, turning Chinese, Japanese, Korean, or accented European text into mojibake. With the BOM, Excel reads the file as UTF-8 directly and accented characters survive intact.
A workbook with several sheets produces one CSV per sheet, because CSV is a flat, single-table format. The downloads are named {workbook}-{sheet}.csv and zipped together when there is more than one.
Supported Formats
| Format | Extension | Notes |
|---|---|---|
| Excel 2007+ workbook | .xlsx | All sheets exported |
| Macro-enabled workbook | .xlsm | Macros are ignored; only data is exported |
| Legacy Excel 97–2003 | .xls | Read via SheetJS BIFF parser |
| Password-protected (file-open) | .xlsx / .xls | Not supported — the file is genuinely encrypted |
vs. “Save As CSV” in Excel
| This tool | Excel “Save As” | |
|---|---|---|
| Install required | No — runs in any browser | Yes — needs a full Excel license |
| Batch conversion | Yes — drop many files at once | No — one workbook at a time, and only the active sheet |
| All sheets in one go | Yes — every sheet exported and zipped | No — you must repeat Save As for each sheet |
| Encoding | UTF-8 with BOM, always | Depends on system locale; often ANSI on Windows |
| Privacy | Local — file never leaves your device | Local, but requires the desktop app |
Limitations
- Formulas are exported as their last calculated values — CSV has no formula concept.
- Formatting, colors, merged cells, charts, and images are not part of CSV and are not carried over.
- Files that demand a password before opening are genuinely encrypted and cannot be read without it.
- Very large workbooks may take a few seconds; everything still happens on your device.
Frequently Asked Questions
Is this XLSX to CSV converter really free?
Yes — 100% free, no sign-up, no watermarks, and no file-count limits. All conversion happens in your browser.
Will my Excel file be uploaded anywhere?
No. The file is parsed and converted entirely in your browser with JavaScript. It never leaves your device.
What happens to workbooks with multiple sheets?
Each sheet becomes its own CSV file. If there is more than one sheet, the CSVs are bundled into a ZIP for download.
Why does my CSV need a BOM?
The BOM tells Excel the file is UTF-8. Without it, Excel often misreads the encoding and non-ASCII text (Chinese, Japanese, accented letters) shows as garbage.
Are formulas preserved in the CSV?
No. CSV stores values only, so each formula cell is written as its last computed result — the same behavior as Excel’s own Save As CSV.
Can I convert a password-protected file?
Only if the password is for editing. A file that requires a password to open is truly encrypted and cannot be converted without it.
How are commas, quotes, and line breaks inside cells handled?
They are escaped per RFC 4180: the field is wrapped in double quotes and any inner quote is doubled, so the CSV stays parseable by Excel, Google Sheets, and every standard CSV reader.
Does it work on old .xls files?
Yes. Legacy Excel 97–2003 files are read through SheetJS’s BIFF parser and converted the same way.
Related Tools
Want the full walkthrough? Read How to Convert XLSX to CSV Without Opening Excel — step-by-step instructions, the manual Excel method, and FAQ.
Need to view or edit the spreadsheet before converting?
Open the free online Excel editor