Split, convert and clean CSV files of any size
Why Excel and the free converters choke on your file
Excel stops at 1,048,576 rows. Google Sheets stops at 10 million cells. Most free online CSV converters cap uploads somewhere between 5 MB and 100 MB, because every megabyte you send costs them bandwidth and server time. A 400 MB export from a database or an ad platform hits all three walls at once.
BigCSV works differently: it never uploads anything. The file is read straight off your disk by the browser, streamed through in chunks, and written back out locally. That means there is no size limit beyond your own machine's memory, and no copy of your data on anyone else's server — which matters when the export contains customer emails, salaries or order history.
What it does
- Split a large CSV into equal parts of N rows, header repeated on each.
- Convert to Excel, JSON, NDJSON or TSV.
- Extract specific columns and drop the rest.
- Remove duplicate rows across the whole row or one key column.
- Filter rows by a condition and export only the matches.
Common questions
Is my file uploaded anywhere? No. Open your browser's network tab and run an operation — you will see no requests. The page is static and the processing is JavaScript running on your machine.
How big a CSV file can it handle? Scanning and splitting stream through the file, so they are limited mainly by disk read speed rather than a fixed cap. Excel export holds the sheet in memory, so keep .xlsx output under about one million rows.
Does it work offline? Yes. Once the page has loaded you can save it and it keeps working with no connection.