Scrub Tools · free, private data tools

CSV Splitter and Merger

Split a big CSV into smaller files that an importer or Excel will accept, either every N rows or one file per value in a column. Or merge several CSVs into one, with columns matched by name even when they are in a different order. Every split file keeps the header row. All of it happens in your browser.

How it works and privacy

Splitting copies the header into each part and fills it with the next block of rows or the rows for one column value. Merging lines up columns by name and builds one combined file. The page is plain HTML and JavaScript that runs on your device: your data is read and processed in this browser tab and is never uploaded, stored on a server or shared. There are no tracking cookies. The only network request this page can make is the optional Pro license check, which sends just your license key to Gumroad.

How to use

  1. Pick Split or Merge.
  2. To split: open one CSV, then choose rows per file or a column to split by.
  3. To merge: choose several CSV files at once (hold Ctrl or Cmd to select more than one).
  4. Press the button, then download each file. Split files download one at a time with their own buttons.

Free and Pro

Free: up to 200 rows per output file, and up to 3 files merged at once. Pro: no row or file limits.

Questions

How do I split a CSV file that is too big for Excel?

Open it here and choose a row count below Excel's limit of 1,048,576 rows per sheet, for example 500,000. Each part keeps the header row so it opens cleanly on its own. Very large files are limited by your device's memory, since nothing is uploaded.

Can I split a CSV into one file per customer, state or category?

Yes. Choose "One file per value in column" and pick the column. You get one file per distinct value, named after the value. Rows with a blank value go into a file ending in "blank".

What happens when the files I merge have different columns?

Columns are matched by name, ignoring upper and lower case and extra spaces, so "Email" and " email " line up. Columns that only some files have are added, and rows from other files get empty cells there.

Why do split files download one by one instead of as a zip?

To keep the tool small and fully offline, it creates each file in your browser and gives it its own download button. Your browser may ask once whether to allow multiple downloads.

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