Why clean your CSV in the browser?
Most “CSV cleaner online” tools upload your file to a server you don’t control. That’s a problem when the file holds customer emails, phone numbers, donor lists, or anything you wouldn’t paste into a random website. This tool is different: every step runs locally in your browser with plain JavaScript. There is no upload, no account, and no network request — open the page, switch off your Wi‑Fi, and it still works. When you download the result, the file is generated on your device from data that never left it.
How to split a name column into first and last
- Load your CSV (choose a file or paste the text).
- Pick the column that holds the full name.
- Click Split into First / Last and download the result.
Names like John Smith become First = John, Last = Smith. A middle name stays with the last name (Mary Jane Watson → Mary / Jane Watson) so nothing is lost. Names written last-name-first, like Smith, John, are detected automatically — or force the order if your data is consistent.
How to dedupe a CSV keeping the newest row
- Load your CSV.
- Tick the key column(s) that define a duplicate — often
Email. - Choose the date/updated column, then click Remove duplicates (keep newest).
For every group of rows that share the same key, only the row with the most recent date is kept — so you remove duplicate rows without losing the latest information. Keys are matched case-insensitively and trimmed of surrounding spaces (JOHN@x.com matches john@x.com).
A careful CSV parser (RFC 4180)
Messy exports break naive splitters. This tool parses CSV to the RFC 4180 rules: quoted fields, commas inside quotes ("Smith, John" stays one value), escaped quotes ("" → "), newlines inside a field, and both LF and CRLF line endings. The delimiter (comma, semicolon, or tab) is auto-detected from the header. Output is re-quoted correctly so it opens cleanly in Excel, Numbers, Google Sheets, or your next import.
FAQ
Does my CSV get uploaded anywhere?
No. All parsing, splitting, and deduplicating happens in your browser. There is no fetch, no XHR, no server — the page makes zero network calls. Your file never leaves your device.
Is this CSV cleaner really free?
Yes, this web tool is free to use with no sign-up. If you regularly clean confidential data, need to batch many files, or want to save and replay a full cleanup recipe, that’s what the paid Rowmend for Mac app is for.
What happens to middle names when I split?
The first word becomes the first name and everything after it becomes the last name, so a middle name is preserved rather than dropped. If your data is written Last, First, the part before the comma is the last name.
Which date formats work for “keep newest”?
ISO dates like 2024-06-30 and 2024-06-30T14:00:00Z are the most reliable, and common formats such as 06/30/2024 and June 30, 2024 are understood too. Rows whose date can’t be read are treated as older than any dated row.