Clean a CSV file online, free, without uploading it
Most online cleaners ask you to upload your file to their servers. Klerio's free cleaner works in your browser: you drop the file in, see every change before it's made, and download the result. No account, no email address.
How it works
- Open the free cleaner and drop in a CSV or Excel file.
- Pick what to fix: spaces, empty rows, emails, phone numbers, UK postcodes, dates, capitals in names.
- Check the list of changes, including anything left alone because it was unclear (like 04/05/2026).
- Download your clean file as CSV or Excel.
Why Klerio
- See every change first: Each fix is listed before you download, with the before and after.
- Never guesses: Dates that could be day-first or month-first are left alone and flagged, not changed.
- IDs are protected: Columns that look like IDs or codes keep their leading zeros and aren't rewritten.
- Free and private: No sign-up, no limit on files, and nothing is uploaded.
Common questions
Is it really free?
Yes. No account and no limit. The paid app adds duplicates, comparing versions, history for each client and automatic workflows.
What file types work?
CSV, TSV and text files, Excel workbooks (.xlsx, .xlsm) and JSON.
What about formulas in my data?
Values that a spreadsheet would run as a formula (starting with = or @) are kept as text in the files Klerio writes, so a cleaned file can't run anything when it's opened.