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MyDataFixer

CSV Validator

Check a CSV file for missing or duplicate headers, uneven rows, broken quotes, the wrong delimiter and encoding problems before you import it anywhere.

Open a CSV file to check it. Repairs are shown before they are applied and can be undone. Everything happens on your device: the file is not uploaded and is never changed; you download a repaired copy.

Your file is read by your browser on this device. It is not uploaded to our servers.

How the CSV Validator works

  1. Open a CSV, TSV or TXT file. MyDataFixer detects the text encoding and the column separator; both can be changed if the file was read wrongly.
  2. Nine checks run: text encoding, column separator, the number of fields in every row, column names, quotes, line endings and blank lines, hidden control characters, Excel and Google Sheets limits, and extra separators at line ends.
  3. The verdict says whether the file is valid and whether it will import cleanly. Each problem card shows the exact line as written in the file, with its line number.
  4. Repairs are offered with a preview: add empty cells to short rows, remove empty extra fields, fix column names, remove spaces around names, remove blank lines, remove hidden characters, and add apostrophes before values that start like formulas.
  5. Download the repaired file with the separator (comma, semicolon or tab), line endings (CRLF or LF) and encoding (UTF-8 with or without BOM) you need. It is checked before it is offered.

Example

A CSV export won't import into a database. The validator shows “Not a valid CSV file: 2 errors”: row 33 has 6 fields instead of 4, and its line reads 1031,Ben,Smith, J,x@example.com,Rome — the comma inside “Smith, J” was never put in quotes. It also finds a column without a name and two columns both called “email”.

“Fix column names” renames them “Column C” and “email (2)”. Row 33 is not changed automatically, because the right fix can't be known; you correct it by tapping the cells, then download the file as UTF-8 without BOM for the database.

What the CSV Validator never does

  • Upload your file or change the original.
  • Repair what can't be known for sure: extra fields that contain data, quotes that never close, and characters that couldn't be read are explained, not guessed.
  • Replace unreadable characters silently. If the chosen text encoding doesn't fit the file, a warning or an error says so.
  • Include adding empty cells to short rows in “Fix all”: short rows can mean values shifted into the wrong columns, so that repair is always shown on its own.

Good to know

  • The validator checks the structure of the file. To check the values themselves (dates, emails, duplicates), use the Spreadsheet Error Detector.
  • The text encodings offered are UTF-8, Windows-1252 and ISO-8859-1 (and UTF-16 when the file starts with a byte-order mark).
  • Without a byte-order mark (BOM), Excel may show accented letters wrongly when the file is double-clicked; databases usually expect no BOM.

Questions and answers

Is my file uploaded?

No. Your browser opens the file on your device and every check, fix and download happens there. The contents of your file are not sent to MyDataFixer's servers or to anyone else, and your original file is never changed.

What makes a CSV file invalid?

Rows with a different number of fields, quotes that never close, unreadable characters, hidden control characters, and — when the first row holds column names — empty or duplicate column names.

My file uses semicolons. Does that work?

Yes. The separator is detected automatically (comma, semicolon, tab or pipe), and you can choose it yourself if the file was read wrongly. The download can use comma, semicolon or tab.

Why are accented letters shown wrongly?

The file was probably saved in a different text encoding. Choose another encoding (for example Windows-1252 for files from older Excel versions); the file is read again and is never changed.

What does “UTF-8 without BOM (for databases)” mean?

A BOM is an invisible marker at the start of the file. Excel uses it to recognise UTF-8; many databases and scripts expect files without it. Choose whichever the program you import into needs.

Can I check a file without a header row?

Yes. Untick “First row contains column names”: the first row is then treated as data and column names are not checked.

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