Can I open a password-protected workbook?

No. Remove protection in Excel first, then upload the unlocked .xlsx.

No. Save as .xlsx. Binary .xls is rejected with that message.

How do multiple sheets download?

Excel to CSV can zip every sheet as its own CSV. CSV to Excel always writes one sheet.

What happens to merged cells?

The top-left value is kept. Other cells in the merge may be empty.

Is UTF-8 BOM included?

Excel to CSV turns BOM on by default so Excel on Windows opens the file. You can turn it off.

Excel ⇄ CSV

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About Excel ⇄ CSV

Tabs are Excel to CSV and CSV to Excel. Both directions are on this page. Excel to CSV reads an unprotected .xlsx, lets you pick a sheet, previews 20 rows, and downloads that sheet as CSV (UTF-8 BOM on by default). Several sheets can download as a zip of CSVs. CSV to Excel reads a CSV (paste or upload), detects or sets the delimiter, and builds a real .xlsx with a bold header and a frozen first row on Sheet1.

Legacy .xls is rejected. Password-protected workbooks cannot be opened. Merged cells keep the top-left value. CSV to Excel is one sheet per file. There is no zip on the way back to Excel.

How to use Excel ⇄ CSV

1Pick a tab. Excel to CSV or CSV to Excel.
2Add the file. Unprotected .xlsx for Excel to CSV. CSV file or paste for CSV to Excel.
3Choose a sheet or delimiter. Excel to CSV: pick a sheet, or zip every sheet. CSV to Excel: Auto-detect or set the delimiter.
4Download. Download this sheet, Download all sheets as zip, or Download XLSX.

Excel to CSV

Upload only (no paste). Sheet lists name and row count. Download this sheet plus Copy for the CSV text. Download all sheets as zip appears when the workbook has more than one sheet. Empty sheets are skipped. Stats show Sheets, Rows, Columns, and the active sheet name.

CSV to Excel

Upload or paste. Delimiter: Auto-detect, Comma, Semicolon, Tab, or Pipe. Preview 20 rows. Download XLSX (the button reads Building while the workbook is created). Numbers and true/false in the CSV are typed in the workbook. CSV to Excel has no Copy. One CSV becomes one sheet named Sheet1.

Limits and privacy

Excel to CSV and CSV to Excel both run in your browser. Uploads are 15MB each. Paste on CSV to Excel is not size-capped. Files are not uploaded. No account.

FAQs

Can I open a password-protected workbook?: No. Remove protection in Excel first, then upload the unlocked .xlsx.
Is .xls supported?: No. Save as .xlsx. Binary .xls is rejected with that message.
How do multiple sheets download?: Excel to CSV can zip every sheet as its own CSV. CSV to Excel always writes one sheet.
What happens to merged cells?: The top-left value is kept. Other cells in the merge may be empty.
Is UTF-8 BOM included?: Excel to CSV turns BOM on by default so Excel on Windows opens the file. You can turn it off.