Text file splitter
Split large text or a file into parts by lines, bytes, characters or a custom delimiter, with CSV header repetition, custom name prefix and extension, per-part size and line count, and individual downloads.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
The file is read locally and never uploaded.
Parts
part-01.csvSize: 37 BLines: 3Characters: 37part-02.csvSize: 38 BLines: 3Characters: 38part-03.csvSize: 24 BLines: 2Characters: 24
Summary
Parts: 3 Total bytes: 99 B Total lines: 8
What this tool does
- Cut a big CSV, log file or mailing list into chunks that fit an import limit — split by lines, bytes, characters or a delimiter.
- For CSV work, enable "keep header row" and every part repeats the first line, so recipients still know what each column means.
- Split by bytes when a hard size cap matters: the byte mode counts UTF-8 bytes and never cuts a multi-byte character in half.
- Control the output names (prefix, zero-padded index, extension — e.g. part-01.csv) and download each part straight from the list.
Example
Input
id,name,role 1,Ada,admin 2,Bob,editor 3,Cara,viewer
Output
part-01.csv id,name,role 1,Ada,admin 2,Bob,editor part-02.csv id,name,role 3,Cara,viewer
This is the result of "2 lines per part" with the header row kept and the csv extension: the header appears in every part.
Frequently asked questions
Can splitting by bytes break Chinese characters?
No. The byte mode adds up UTF-8 byte lengths and moves to the next part when the next character would not fit, so a character is never split across parts. A part may therefore end up slightly smaller than the limit you typed.
Why does every part start with the header row?
Because "keep header row" is enabled. The first line is treated as the header, the remaining lines are chunked, and the header is prepended to each part. Turn the option off for plain text that has no header.
Where does the delimiter go when I split by delimiter?
It stays at the end of the preceding part instead of being dropped. Concatenating the parts in order therefore reproduces the original text exactly.
Are my files uploaded anywhere?
No. Files are read through the browser file API and every part is built and downloaded inside the page; no network request is made and it works offline.
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