📊 CSV Splitter & Merger
Split a large CSV into smaller files by row count — every chunk keeps the header — or merge several CSVs into one, deduplicating repeated header rows. Free, quote-aware, runs entirely in your browser.
About
This tool handles two common CSV workflow tasks — splitting and merging — without sending any data to a server. In Split mode, you set how many data rows each output file should contain; the tool slices the original CSV and packages every chunk as a separate file inside a single ZIP archive, with the original header row preserved at the top of each chunk. In Merge mode, you load two or more CSV files; the tool concatenates them in order, keeping only the first header row and discarding any subsequent header rows that appear at the top of later files. A quote-aware parser ensures that commas or newlines inside quoted fields are never mistaken for field or row boundaries, so structured data such as addresses or multi-line notes survives both split and merge intact. Everything runs locally in your browser, so large files are processed quickly without network latency and your data never leaves your device.
How to use
- Choose Split or Merge mode using the tab at the top of the tool.
- Drop your CSV file(s) onto the upload area, or click to browse and select from your device.
- In Split mode, enter the maximum number of rows per output file. In Merge mode, arrange the files in the order you want them joined.
- Click the action button to process. Split produces a ZIP of numbered CSV chunks; Merge produces a single combined CSV file.
- Download the ZIP or merged CSV directly to your device. No files are uploaded anywhere.
FAQ
- Does every output chunk include the original header row?
- Yes. The first row of your CSV is treated as the header and automatically prepended to every chunk, so each split file is immediately usable on its own.
- How does the tool handle repeated header rows when merging?
- The header from the first file is kept. Any row at the start of a subsequent file that exactly matches the header is dropped automatically, so the merged output has exactly one header row.
- What happens if a field value contains a comma or a line break?
- The built-in quote-aware parser correctly identifies RFC 4180 quoted fields, so commas and newlines inside double-quoted values are treated as part of the field and never as delimiters.
- Is there a file size or row count limit?
- There is no artificial limit imposed by the tool. The practical ceiling is your browser's available memory. Modern browsers handle files of hundreds of megabytes comfortably.
- Are my CSV files sent to a server?
- No. All processing happens locally inside your browser using JavaScript File and Blob APIs. Your data never touches a network — it stays entirely on your device.