KOENJP

.xlsx ↔ CSV Converter

XLSX · CSV

Convert a sheet from an .xlsx or .xls file to CSV, or a CSV to .xlsx. Choose comma, semicolon or tab and add a UTF-8 BOM. Nothing is uploaded.

Your files are processed right here in your browser. Nothing is uploaded or stored on a server.SheetJS CE 0.20.3 (Apache-2.0)

Good to know. Very large files may be slow or run out of browser memory. CSV keeps only the calculated values — formatting, formulas and merged cells are dropped. Password-protected files can't be opened.

HOW TO

How to use

  1. Drop an .xlsx, .xls or .ods file, or a CSV file.
  2. For a spreadsheet, pick the sheet, the delimiter (comma, semicolon or tab) and whether to add a BOM.
  3. For a CSV, the encoding and delimiter are detected automatically, and you can change them.
  4. Check the preview, then download the CSV or .xlsx.
PAIRS WELL WITH

Pairs well with

FAQ

FAQ

Non-English text looks garbled when I open the CSV.

Turn on “Add UTF-8 BOM” before downloading. The BOM tells spreadsheet apps the file is UTF-8, so the text shows correctly.

Are formulas and formatting kept in the CSV?

CSV holds plain text only, so formulas are saved as their calculated values and formatting is dropped. With “Keep cell formatting” on, values are written as displayed, like 1,234 or 10/14/2026.

Are my files uploaded?

No. The conversion runs entirely in your browser and the file is never sent anywhere.