Split large CSV files online.

When do you need a CSV splitter?

CSV files grow faster than the tools that need to ingest them. A 200 MB customer export from a CRM, a 1.5 GB orders dump from an ERP, a multi-million row event log — none of these can be opened in Excel and most cannot be imported as a single file into HubSpot, Salesforce, Mailchimp, Klaviyo or a typical batch import pipeline.

Splitting the CSV into smaller, equally-shaped partials solves the import-ready chunk problem without writing a script. The most common reasons people split a CSV by rows:

• CRM imports — fits HubSpot, Salesforce, Pipedrive row or size caps
• ERP migrations — break a multi-million row dump into manageable batches
• Email platforms — Mailchimp, Klaviyo and Sendgrid cap audience uploads
• Database loads — keep each partial under the timeout of LOAD DATA INFILE
• Sharing by email — most providers reject attachments above 25 MB
• Splitting for parallel processing — feed each partial to a different worker

How the CSV splitter works

MessyMatch reads the file in your browser using a Web Worker. The first row is detected as a header automatically, even when your data contains dates, phone numbers or accented values. From that point on the splitter streams the file: it never holds the whole CSV in memory more than once, which is why it works on files much larger than Excel can open.

You then choose how to cut the file. The simplest is split by row count — every output file gets exactly N rows except the last one, which may be smaller. You can also split by file count (N equal partials), by byte size (each partial under a target MB cap, useful for upload limits), or by a column value (one partial per unique value of a column — handy for partitioning orders by country, region or salesperson).

Keep headers in every partial

The default is to repeat the header row in every output file. That is what most importers expect — each file should be self-contained so column meaning is preserved. If your downstream tool concatenates the partials back together, you can turn the option off and only the first partial will carry the header.

Download all partials as a ZIP

When the split finishes you get a list of every partial with its row count. Download them one by one or grab the whole batch as a single ZIP. File names follow the pattern name_0.csv, name_1.csv, name_2.csv by default; you can change the template to anything that fits your downstream tool.

Browser-first by design

CSV contents are processed inside your browser via a Web Worker and are not transmitted to our servers. Our servers do not have an endpoint that ingests file contents — the Web Worker reads the file from disk, splits it locally and hands the partials back to the browser for download. We only record metadata about the operation (row count, file size, format, elapsed time) for abuse limits and analytics. See the privacy policy for the full list of what we collect and what we do not.

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