How to split a large CSV file
- Drop the CSV file. The number of data rows is shown.
- Choose either a number of rows per file (for example 1,000 for an import limit) or the number of files you want.
- Keep "Repeat the header row" ticked so every part has the column names, then press Split to download a ZIP of the parts.
- To combine files instead, switch to Merge CSVs, drop several files with the same columns, and download one merged CSV.
Why split or merge CSVs?
Many tools limit uploads: CRMs, email marketing platforms, e-commerce importers and online spreadsheets often cap a single import at a few thousand rows or a few megabytes, and Excel cannot open more than 1,048,576 rows. Splitting a big export into chunks with the header repeated in each makes it importable. Merging is the reverse: combining monthly exports, survey batches or reports from different sources into one file for analysis, optionally with a column showing which file each row came from.
The splitter understands CSV quoting, so fields containing commas or line breaks inside quotes are never cut in half, and it keeps the original row order and text exactly, including a UTF-8 byte-order mark if the file had one. Everything runs in your browser, so even confidential customer lists never leave your device.
Is there a file size limit?
Only your device's memory. Files of several hundred megabytes usually work on a computer.
Are quoted line breaks handled?
Yes. A line break inside a quoted field stays inside that record.
What if the merged files have different columns?
You get a warning. Align the columns in a spreadsheet first, or untick the header option to keep all headers.