Excel to CSV Converter

Excel to CSV Converter

Convert XLSX and XLS sheets to clean CSV in your browser, pick the sheet and delimiter, nothing uploaded.

Drop an Excel file here

XLSX, XLS, XLSM, XLSB or ODS. Your file stays on this device, nothing is uploaded.

How it works

  1. Open your spreadsheet. Drop an XLSX, XLS, XLSM or ODS file on the page or choose it. It is read by your browser, not uploaded.
  2. Pick the sheet and format. Choose the sheet, the delimiter, the line ending, a UTF-8 byte order mark and how dates and formulas are written. The preview updates as you go.
  3. Download the CSV. Save the sheet as a CSV named after your file, copy it to the clipboard, or save every sheet as its own CSV.

Questions, answered

Are my files uploaded anywhere?

No. Excel to CSV Converter runs entirely in your browser. Your spreadsheet is read into memory on your device, converted with JavaScript, and never sent to a server. You can disconnect from the internet and it keeps working.

Why do accents look broken when I open the CSV in Excel?

Excel guesses the encoding of a CSV file and often guesses wrong. Keep the "UTF-8 + BOM" encoding option: the byte order mark tells Excel the file is UTF-8, so names like Renée open correctly. Some import tools dislike the mark; choose "UTF-8, no BOM" for those.

Comma or semicolon: which delimiter should I pick?

Use whatever the program that imports the file expects. Comma is the standard. Excel in many European locales expects semicolons because the comma is the decimal separator there. Values that contain the delimiter, quotes or line breaks are quoted automatically either way.

What happens to dates, formulas and merged cells?

Dates are written as ISO dates (2026-07-31) or exactly as displayed, your choice, and no time zone is applied, so the date stays the one shown in Excel. Formulas export their last computed value or their formula text. Merged cells keep only the top-left value, like Excel's own CSV export. Empty rows at the end are trimmed.

Is it really free, and does it work offline?

Yes. It is open source under the MIT license, with no account, no file size cap, no daily limit and no ads. After your first visit the page is cached by a service worker, so it loads without a connection. If it saves you a paid subscription, you can say thanks on Ko-fi.

Was this written by AI?

Yes. Excel to CSV Converter was generated by Claude Code from a written specification inside an automated pipeline, with a test suite that runs in a real browser. The full source is on GitHub, so you can read every line before you trust it with your files.

Built by one person, given away for free

Excel to CSV Converter is a free alternative to paid tools like Convertio Excel to CSV. If it earns a place in your bookmarks, a coffee keeps the updates coming.

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