Split CSV files by size or rows — without uploading them.

No upload. The tool is 100% client-side JavaScript — your file is read by your browser's built-in File API and all the splitting happens on your device. There's no server-side component, which is why we can make the promise. You can verify it in your browser's developer tools: the Network tab will show zero outgoing requests with your file in them.

If you need extra assurance for compliance (HIPAA, GDPR, financial data), turn off your Wi-Fi after the page loads, process the file, then turn it back on. The tool still works, which proves no upload happens.

Yes — always. The original header row is copied into every output file. This is what makes each part importable independently into Salesforce, HubSpot, databases, or any other system expecting a header row. You don't have to do anything special to enable this.

There's no hard limit from us — the constraint is your browser's available memory. In practice:

• Files up to 500 MB work comfortably on most modern machines
• 1–2 GB files work on Chrome or Edge with plenty of RAM
• Beyond 2 GB, browser string limits start to bite — if you hit an error, split by row count (smaller chunks process faster)

If a file crashes the tab, reload and try "By row count" with 10,000 or 50,000 rows per file. The streaming writer is gentler on memory than the size-based splitter.

Pick "By file size" mode and click the "Salesforce / HubSpot — 25 MB" preset. That's it. The tool splits your CSV into files ≤ 25 MB, each with the full header row, ready to upload into the Data Import Wizard one at a time. The 25 MB preset also works for HubSpot's contact import.

If you have more than about 10 GB of data, consider Salesforce Data Loader instead — it's built for larger bulk imports.

Yes. Drop your .xlsx or .xls file onto the tool and it's read natively — you don't need to convert it to CSV first. You can also output the splits as XLSX if you prefer to keep the Excel format (booleans and formatted dates survive the round-trip).

One note: if your Excel file has multiple sheets, only the first sheet is processed. To split other sheets, save them as separate files first or use the Merge tool after.

This is almost always an encoding issue. Most CSVs exported from older Excel on Windows are in Windows-1252 rather than UTF-8. The tool auto-detects encoding on read and handles both — but if your original file was saved without a BOM and uses unusual characters, detection can be wrong.

The fix: re-save the original file as "CSV UTF-8 (Comma delimited)" from Excel, or open it in a text editor, save as UTF-8, then drop into the tool. The output is always UTF-8 with BOM, so the splits will import cleanly into Salesforce, HubSpot, and Google Sheets.

Yes. This was a common bug in earlier versions and in most competing tools. The splitter preserves your original cell contents as strings — a ZIP code "01234" stays "01234" and won't get mangled to 1234.

For XLSX output specifically, the tool is careful to keep leading-zero strings as text rather than auto-casting to numbers (Excel's default behavior that breaks so many imports).

Use "By column value" mode. Pick a column — say "region" — and you get one output file per unique value. So a dataset with regions "North", "South", "East", "West" produces four files, each containing only rows for that region, headers included.

This is useful for: splitting orders by country, emails by campaign, transactions by month, customers by assigned sales rep, or any other categorical breakdown. Rows where the column is blank go into a file called (blank).csv.

CSV files compress extremely well — typically 80–90% reduction. When you click "Download all as ZIP", the tool runs standard deflate compression on each part. A 500 MB total of CSV files often becomes a 60–80 MB ZIP. The individual .csv files inside the ZIP are the original full size — the compression is only in transit.

Yes. Configure your split method, row count, output format, then click "💾 Save settings". Your preferences are stored in your browser's localStorage and load automatically next time. "🗑 Clear" removes them. Nothing is sent to a server — storage stays on your device.

Drop your file in, pick By file size, and click the Salesforce / HubSpot — 25 MB preset. Leave Include header in each output file checked so every part imports independently with correct column names. You'll get a ZIP with files named yourfile_part01.csv, yourfile_part02.csv, etc. Import them one at a time in order — queuing imports simultaneously makes errors hard to trace.

Yes. Choose By column value and pick the column to split on — e.g. country, assigned_rep, or customer_id. The tool creates one output file per unique value, named using the value itself (yourfile_United-States.csv, yourfile_Canada.csv, etc.). Works for any non-empty column. Empty values get grouped into a single _blank.csv file.