How to Split a CSV by Column
- Choose or drag in your CSV file. The first rows are shown so you can check it was read correctly.
- Pick the column that holds the groups you want, for example Country, Sales rep or Order status.
- Press Split File and wait for the progress bar. A 1 GB file usually takes under a minute on a recent laptop.
- Download everything as one ZIP, save all files into a folder, or download individual files from the list.
A Typical Example
Say you have a year of orders exported from your shop system, with a store column. Your managers each need only their own store's orders. Splitting by store produces files like this:
| Output file | Contains |
|---|---|
Berlin.csv | Header row + every order where store is Berlin |
Lyon.csv | Header row + every order where store is Lyon |
Paris.csv | Header row + every order where store is Paris |
blank.csv | Header row + orders with no store filled in |
Rows keep their original order inside each file, so a file sorted by date stays sorted by date.
Why Not Just Use Excel Filters?
For a small file you can filter a column in Excel, copy the visible rows to a new sheet and save it, once per value. That breaks down quickly. With forty stores it is forty rounds of filter, copy, paste and save. And Excel cannot open a sheet with more than 1,048,576 rows, so a large export will not even load: Excel stops at that row and warns that the file was not loaded completely.
Excel also changes data when it opens a CSV. Postal codes like 00742 lose their leading zeros, long account numbers turn into 4.52E+15, and some codes are converted into dates. If you save the filtered rows back to CSV, those changes are saved too. This tool never interprets values; it copies the text of each row as it is.
How It Handles Large Files
Most online CSV tools load the whole file into your browser's memory, which is why they stop working somewhere between a few hundred megabytes and a couple of million rows. This tool streams the file instead: it reads about 4 MB, writes the rows to their output files, and moves on. Memory use stays roughly the same whether the file is 50 MB or 20 GB.
Output files are written to your browser's private storage on your own disk rather than held in memory, and only a handful are open at any moment, so splitting into thousands of files works too. It correctly handles quoted values that contain commas or line breaks, files saved with semicolons or tabs, and files from older Windows programs that are not UTF-8.
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