How to fix a broken or malformed CSV file (wrong delimiters, encoding errors, uneven columns)
Practical steps to diagnose and repair a CSV file that won't open cleanly: wrong delimiter detection, character-encoding issues, and rows with the wrong number of columns.
Before you work through this by hand: you can check your own CSV free and see which of these problems your file actually has — duplicate rows, near-duplicates, broken quoting, encoding damage. It runs in your browser tab, nothing is uploaded, and there's no signup or email.
1. Check the delimiter
Most CSV problems start with the wrong delimiter being assumed. Open the file in a plain text editor (not Excel) and look at a data row: is it separated by commas, semicolons, or tabs? Many exports from European systems use semicolons.
2. Check the character encoding
If you see garbled characters like é instead of é, the file is likely UTF-8 being read as a different encoding (or vice versa). In a text editor, try re-opening or re-saving explicitly as UTF-8.
3. Look for uneven row lengths
A common corruption source is a text field that itself contains a comma or a stray line break, which shifts every column after it. Proper CSV files quote such fields, but manually edited or poorly exported files sometimes don't. Scan for rows with a different number of commas than the header row.
4. When manual fixes aren't enough
Once a file has many of these issues mixed together, a tool that can detect delimiter/encoding automatically, flag uneven rows without silently dropping data, and let you review each fix is usually faster and safer than hand-editing.
See also: our Python encoding-error guide for a deeper look at fix #2, and the CSV cleanup checklist for a full pre-import review.
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