Split large CSV file into smaller files
Too large for your import tool, API rate limit, or email attachment? Upload your CSV and split it by row count, file size, or column value — download all parts as a ZIP in one click.
Upload your CSV to split
CSV, XLSX, or JSON — any size
Free account — takes 10 seconds to sign up
After upload: go to the Split file tab → choose split mode → Preview → Download ZIP.
Three ways to split a CSV
By row count
Specify how many data rows each output file should contain. CSViser creates as many
files as needed, each with the same header row. For example, a 10,000-row file split
into chunks of 1,000 rows produces 10 files: export_001.csv through
export_010.csv. Useful for API import limits (e.g. Mailchimp's 50,000-contact
batch, Shopify's 1,000-product import).
By file size
Specify a maximum size in kilobytes per output file. CSViser adds rows until the next row would exceed the limit, then starts a new file. Useful for email attachment limits or upload form size restrictions.
By column value
Choose a column (e.g. Country, Category, Region) and CSViser
creates one file per unique value in that column. A 5,000-row file with a Country column
containing 12 distinct values produces 12 files, each named after its value:
export_US.csv, export_DE.csv, etc. Useful for distributing
data to regional teams or per-category import pipelines.
Headers in every output file
Every output file includes the original header row. You don't need to add headers back manually after splitting — each part is a self-contained, valid CSV file ready for import. Trailing blank rows (a common artefact of spreadsheet exporters) are stripped before splitting so they don't inflate the last chunk.
Output: ZIP archive
All parts are packaged into a single ZIP file and streamed to your browser for download. Nothing is stored on the server after the download completes. The ZIP is generated in memory — no temporary files are written to disk.
Frequently asked questions
How do I reassemble the parts later?
Use the Append rows tab in CSViser to merge split files back together — upload the second file and its rows are appended below the first, with header deduplication. Repeat for each additional part.
Can I preview how many files will be created?
Yes. Click Preview before downloading — CSViser shows "→ N files" so you can adjust the split parameters before committing.
Is the original file changed?
No. Splitting produces new output files; the original CSV on the server is unchanged. You can continue using other tabs (Fix issues, Deduplicate, etc.) on the original file.