Seeing é, ü, ’ or  in your CSV? The text was saved as UTF-8 but read with the wrong encoding somewhere. Upload the file: SheetFix finds the garbled cells, shows every before → after, and gives you a clean UTF-8 CSV or XLSX.
The file is read in your browser, nothing is uploaded to a server.
Only cells with garbled characters change, each one shown before and after.
Get a UTF-8 CSV (with BOM so Excel reads it right) or an XLSX.
The file is UTF-8, but a program opened it as Windows-1252 or Latin-1, splitting each accented letter into two odd characters. Sometimes it was then saved again, baking the error into the file.
Typical mix-ups like é → é, ü → ü, ’ → ’, € → € and stray  before spaces. Double-garbled text is repaired too.
No. A cell only changes when it reverses into valid UTF-8; normal text, other languages and numbers are left alone.
Then the original bytes were already lost when the file was saved. That can't be reversed by any tool; re-export from the source system as UTF-8.
Yes. Free, no account needed, and the file never leaves your browser.
CSV opens in one column in Excel? Get a proper .xlsx.
Fix spaces, emails, phone numbers, dates and capitalization.
Diagnose a damaged .xlsx, recover readable data, download a verified file.
Turn a CSV into an Excel workbook, leading zeros kept.