How to clean a messy CSV safely

Step-by-step approach

Make an untouched copy of the source CSV before editing.
Check whether its delimiter is a comma, tab or semicolon; a semicolon file should not be parsed as comma CSV.
Use the CSV Cleaner to trim whitespace and eliminate truly empty rows.
Review the before/after row counts and download a new CSV.
Open the exported file in your target application to verify leading zeros and international characters.

Try the matching tool

Open CSV Cleaner to work on a local copy. Review the result before importing it elsewhere.

What this does not solve

Browser tools can validate known structures and transform available data, but cannot restore deleted or corrupted bytes, infer unknown business facts, or guarantee that a target system will import every field as intended.