AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I split a large CSV file into smaller files?

Drop your CSV into AnyTool Split CSV, choose how to split it — by row count, by file size, by the value in a column, at blank rows, or by custom row ranges — and click Split. Each output part keeps the header row, and you download them all as a single ZIP. Everything runs in your browser, so even very large files are never uploaded.

  • Split by row count, file size (MB), column value, blank rows, or custom ranges
  • Header row is repeated in every output file by default
  • Files are processed in your browser — nothing is uploaded, no size-limited server
  • Download every part at once as a ZIP, or grab files individually
  • Auto-detects the delimiter (comma, semicolon, tab, pipe) and is RFC-4180 safe

What is

CSV Splitting

Splitting a CSV means dividing one comma-separated-values file into several smaller files, usually so each part fits an upload limit, opens in a spreadsheet, or groups related rows together. A good splitter repeats the header row in every part so each file stays valid on its own, and it can split by a fixed number of rows, a target file size, or the value of a chosen column.

Converters

Related terms

CSVSplit ExcelRow countDelimiter

Frequently Asked Questions

No. AnyTool splits the CSV entirely in your browser, so the file never leaves your device.

AnyTool Split CSV reads your file with the browser File API and does all parsing and splitting in local JavaScript. Nothing is uploaded, there is no account or tracking, and because there is no server round-trip it has no upload size limit of its own — you can split very large CSVs that online uploaders would reject.

Leave "Keep header row in each output file" on — the first row is copied to the top of every part.

By default the tool treats the first row as a header and repeats it at the top of every output file, so each part is a complete, openable CSV. You can turn this off in Advanced options if your data has no header, in which case the first row is treated as data and split like the rest.

Yes. Pick "By Column" and choose a column, and each unique value becomes its own file.

Choose the By Column mode and select which column to group on. Every distinct value in that column gets its own output file — for example one file per region, status, or customer — with the file named after the value. Splitting by column is capped at 500 unique groups to keep the browser responsive.

Use By Row Count for an exact number of rows per file, or By Size to cap each file at a number of megabytes.

By Row Count chops the data into fixed N-row chunks — useful for import limits like 50,000 rows. By Size (MB) packs rows into each file until it reaches your chosen megabyte target, which is handy for email or upload size caps. Both modes show an estimated file count before you split and repeat the header in each part.

Detailed Explanation

Methodology

How Split CSV Works

AnyTool Split CSV reads your file with the browser File API and parses it locally with an RFC-4180-aware parser that auto-detects the delimiter (comma, semicolon, tab or pipe) and preserves quoted fields, embedded commas and newlines. It then re-emits the rows using one of five modes: fixed N-row chunks; a target file size in megabytes; one file per unique value in a chosen column; a new file at each blank row; or hand-picked row ranges such as 1-100,150-200. The first row is treated as a header and repeated at the top of every output part, so each file is a complete, openable CSV on its own.

  • Five modes: by row count, file size, column value, blank rows, or custom ranges
  • RFC-4180 parser handles quotes, embedded commas and newlines correctly
  • Delimiter auto-detected; output delimiter, encoding and line endings configurable
  • Header row repeated in every part by default (can be turned off)
  • All parsing and splitting is client-side JavaScript — no server round-trip
Privacy & Security

Privacy and Large-File Handling

Because the entire split runs in the browser, your CSV is never uploaded, there is no account or tracking, and the page works offline after first load. With no server in the loop there is no per-request upload cap, so files that online uploaders reject can be split locally; the tool reads files up to roughly 200 MB and bundles the resulting parts into a single ZIP with JSZip for one-click download, or you can save each part individually.

  • Files never leave the device — nothing is uploaded
  • No server upload limit; reads files up to about 200 MB locally
  • Output parts can be downloaded together as one ZIP or one at a time
  • UTF-8, UTF-8 + BOM (Excel-friendly) and Latin-1 output encodings
  • No signup, no tracking; works offline after first load
Use Cases

When to Split a CSV

Splitting a CSV is common when a dataset is too big to open in a spreadsheet, too large for an import or upload limit, or needs to be broken out into per-group files. By Row Count fits fixed import limits (for example 50,000 rows per batch); By Size keeps each file under an email or upload megabyte cap; By Column produces one file per region, status or customer; and custom ranges or blank-row splits extract specific sections. Column-value splitting is capped at 500 unique groups to keep the browser responsive.

  • By Row Count suits fixed import batch limits
  • By Size keeps each file under an upload or email megabyte cap
  • By Column produces one file per distinct value, named after the value
  • Blank-row and custom-range modes extract specific sections
  • Column-value splitting is limited to 500 groups to protect browser memory
CSV splitting: in-browser (AnyTool) vs typical online splitters
CapabilityAnyToolTypical online splitters
ProcessingRuns in your browserUsually uploaded to a server
PrivacyFile never leaves deviceFile posted to a third party
File size limitNo upload cap; reads up to ~200 MB locallyOften a strict upload size cap
Split modesRows, size, column, blank rows, rangesOften rows or size only
Header in each partYes, by defaultSometimes only in the first file
OutputZIP of all parts or individual filesVaries
Works offlineYes (PWA)No
Cost / signupFree, no signupOften gated or ad-heavy

Server-based splitters upload your CSV; AnyTool splits it locally and uploads nothing.