CSV cleaner

Q: Is the CSV cleaner free?

Yes. There is no account. Typical sheets up to 1.5 MB and 10,000 rows are supported.

Clean CSV in your browser. Trim cells, fill empty placeholders, and standardize dates, numbers, and booleans. Nothing is uploaded.

Trim Empty n/a Dates Numbers Booleans Dates Numbers

Paste CSV, then Clean CSV.

How to clean a CSV file

Paste CSV or open a .csv file. Delimiter is detected from the first row (,, ;, tab, or |).
Choose date and number locales if the sheet is not US-style.
Click Clean CSV, preview the table, then download cleaned.csv.

What gets standardized

Each column is classified from its values, then rewritten:

Dates become ISO YYYY-MM-DD (with time when the cell has a clock).
Numbers drop currency symbols and thousands separators. Accounting (400) becomes negative.
Booleans such as yes/no, y/n, true/false become true or false. A column of only 0 and 1 stays numeric so IDs are not flipped.
Placeholders like n/a, NULL, and - become empty cells.

Nothing is uploaded

Cleaning runs in this tab. Typical sheets up to 1.5 MB and 10,000 rows are supported. The download includes a UTF-8 BOM so Excel keeps international characters. Need nested JSON instead? Use JSON to CSV. More utilities live on tools.

CSV cleaner FAQ

Does this CSV cleaner upload my file?

No. Parsing and cleanup run in your browser. The CSV never leaves your machine.

How do you tell dates from numbers?

A column is treated as dates, numbers, or booleans when most of its non-empty cells match that shape. Mixed text columns are only trimmed.

Why did 08/01 stay the same month?

Slash dates are ambiguous. Set Dates to US (month first) or EU (day first) before you clean.

Will Excel open the cleaned file?

Yes. The download is UTF-8 with a BOM. Formula-looking values are prefixed so they stay text.

Is the CSV cleaner free?

Yes. There is no account. Use it for exports and lab sheets within the limits above.