CSV cleaner: fix separators, accents and duplicates

Fix the usual problems with CSV files in one go: the wrong separator, accents that show as é in Excel, stray spaces, empty columns and duplicate rows.

Choose the CSV or Excel file

or drop .csv or .xlsx files here

Up to 20 files at a time. Your files stay on this device.

Or paste CSV text
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Your files stay on this device: the conversion runs in your browser and nothing is uploaded. Learn how your files are handled

How to clean a CSV file

  1. Choose the file (CSV, TSV or Excel), or paste CSV text. The tool tells you which separator and text format your file uses.
  2. Tick what to fix. By default, the new file uses commas as separators, is saved so that Excel shows accents correctly, and has spaces trimmed. Removing empty columns and duplicate rows is up to you. Identical rows can be real (two equal payments on one day), so the rows removed are listed.
  3. Check the summary of what will change and the preview, then download the cleaned file.

Common problems this fixes

Everything is in one column in Excel

The file uses a different separator from the one your Excel expects. Excel in Germany, France, Spain, Italy and many other countries uses semicolons. In the US, UK and India it uses commas. Choose the separator your Excel (or the app you are importing into) expects.

Accents and other alphabets look wrong (é, ’, ????)

The file is saved as UTF-8 (the modern standard for text) but Excel opened it as an older Windows format, or the other way round. Under “Save the text”, choose For Excel (accents show correctly). This adds a small invisible marker (a “BOM”) that tells Excel the file is UTF-8. Choose “For other apps and databases (UTF-8)” for databases and code, and “For old Windows programs (Windows-1252)” only for old programs that need it. If the file itself already contains é or ? (it was saved after being misread), the original characters can’t be recovered. Export it again from the program it came from.

Imports fail on duplicates or blank values

Removing exact duplicate rows, empty columns and stray spaces fixes many “duplicate key” and “invalid value” errors in customer databases (CRMs), e-mail tools and online stores. By default, duplicates are rows that are identical in every column after spaces are trimmed. You can also find them by one column, such as an e-mail address, and tick “Ignore upper and lower case” to treat [email protected] and [email protected] as the same. The first row of each group is kept.

What stays the same

  • Row order, column order and the header row, exactly as in your file (or no header row, if your file has none).
  • CSV values are never reformatted: numbers, dates and leading zeros stay exactly as written. Excel files are read the same way as in the Excel to CSV converter: dates become YYYY-MM-DD and cell formatting is dropped.
  • Values in quotes that contain commas or line breaks. They are read properly and written back with the right quotes.
  • Blank rows are always removed, and the summary tells you how many.

Frequently asked questions

How do I change a semicolon CSV to a comma CSV?

Choose the file, keep “Comma” as the separator and download. Values that contain commas are put in quotes automatically, so no value is split by mistake. A simple find-and-replace would break them.

Why does Excel show strange characters, and how do I fix it?

Excel guesses the text format when it opens a CSV, and often guesses wrong for UTF-8 files (the modern standard). Under “Save the text”, choose “For Excel (accents show correctly)” and download the cleaned file. Excel will then show accents and other alphabets correctly.

Which rows count as duplicates?

By default, rows that are identical in every column after spaces are trimmed. Under “Find duplicates by” you can pick one column instead, for example e-mail, to keep one row per address. The first row is kept and later ones are removed. Rows with an empty value in that column are always kept.

Will it change my numbers or dates?

Not in CSV files. Cells are only trimmed (if you choose that) and never reformatted, so dates, amounts and leading zeros stay as they are. From an Excel file, dates are saved as YYYY-MM-DD and number formatting is dropped, as with any CSV export.

How do I make Excel save a CSV with semicolons, or change its separator?

Excel takes the separator from your computer’s region settings. On Windows you can change it under Control Panel → Region → Additional settings → List separator, but that also affects other programs. The simpler way is to save the CSV from Excel as usual, choose it here, pick the separator you need (comma, semicolon, tab or pipe) and download the new file.

What is the difference between CSV and CSV UTF-8 in Excel?

“CSV UTF-8” saves the text as UTF-8, the modern standard, which keeps every letter and alphabet, and adds the small marker Excel looks for. Plain “CSV” uses an older text format that depends on your computer’s settings (often Windows-1252), and letters it can’t store are replaced with question marks. Choose CSV UTF-8 unless an old program asks for the other. This tool’s “For Excel” option saves the file the same way as CSV UTF-8.

How are commas inside values handled?

A value that contains the separator, a quote or a line break has to be wrapped in double quotes, and a quote inside it is written twice: "Smith, John" or "She said ""yes""". The cleaner reads such values correctly and writes them back with the right quotes, so changing the separator never splits a value. Tick “Put quotes around every value” if an import tool needs every value quoted.

How do I remove blank rows from a CSV file?

Choose the file here and download the cleaned version. Blank rows, including rows that hold only separators or spaces, are always removed, and the summary tells you how many there were. To remove columns that are completely empty as well, tick that option.

Is my file uploaded?

No. Cleaning happens in your browser, and the new file is created on your device.