About

Managing large datasets often involves navigating strict import limitations imposed by third-party platforms. Email marketing services, database management tools, and spreadsheet software frequently cap the number of rows or file size allowed per upload. When a dataset exceeds these boundaries, the upload fails or truncates data. Manual separation is time-consuming and introduces a high risk of human error, such as duplicated entries or lost rows.

The List Splitter automates the division of extensive text blobs into smaller, strictly defined segments. By specifying a maximum number of lines per chunk, users can generate multiple output files that comply with specific system constraints. This process preserves data integrity and ensures that headers (if selected) are repeated for every file, maintaining context across all split segments. This utility is critical for developers performing SQL inserts, marketers migrating contact lists, or analysts working with legacy systems that cannot parse multi-megabyte text files.

Formulas

The core logic determines the total number of resulting files (chunks) based on the total line count of the source data and the user-defined limit per file. If L represents the total number of lines in the dataset and n represents the maximum lines allowed per chunk, the total number of chunks k is calculated using the ceiling function:

k = ceil(Ln)

When a header row is preserved, the effective capacity for data lines in subsequent chunks is reduced by 1. The operation ensures that for every set of data S, the union of all generated chunks C_i (excluding redundant headers) reconstructs the original set:

S ≡ k∪i=1 C_i

Reference Data

Platform / Standard	Typical Limit	Recommended Chunk Size
Excel (Old .xls)	65,536 rows	50,000 lines
Excel (New .xlsx)	1,048,576 rows	1,000,000 lines
Mailchimp Import	100 MB (approx)	10,000 - 50,000 lines
MySQL (InnoDB)	Packet Size Config	1,000 - 5,000 inserts
Google Sheets	10,000,000 cells	20,000 rows
Free Email Validators	Variable	500 - 1,000 lines
Twitter Audience	10,000 IDs	10,000 lines
Facebook Custom Audience	Variable (Hash limit)	20,000 lines
Notepad++ (Edit)	2 GB (RAM dependent)	100,000 lines
Standard CSV Upload	Server Timeout	5 MB

Frequently Asked Questions

If you enable the "Preserve Header" option, the tool identifies the very first line of your input as the header. It will then automatically replicate this line at the top of every subsequent chunk. This is essential for CSV files where every split file needs the column names to be valid for importing.

No. The process is strictly structural. The tool reads raw text, detects newline characters (LF or CRLF), and groups lines into new arrays. No character encoding changes or content modification occurs within the lines themselves.

The tool runs entirely in your browser using JavaScript. The practical limit depends on your computer's available RAM and browser capabilities. Generally, text files up to 10MB or 20MB are processed instantly. Files exceeding 100MB may cause the browser tab to slow down during the split operation.

Currently, this specific tool is optimized for line-based splitting (lists, logs, CSV rows). It splits data wherever a line break occurs. If your data uses a different delimiter (like a semicolon) without newlines, you would first need to replace those delimiters with newlines before using this tool.

Browser security protocols often block websites from initiating multiple automatic downloads simultaneously to prevent spam. While the tool processes the split instantly, providing individual download buttons (or copy-to-clipboard options) ensures you have full control over which files are saved to your device.