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Split large TXT, LOG and CSV files
This tool splits a large text file into smaller files – every N lines, into N equal parts, by maximum size or at lines that contain a pattern – and packs the parts into a ZIP. Files of hundreds of megabytes are streamed in your browser.
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How it works
Open the file
Choose a file up to 500 MB, drop it on the page or paste text. Big files are not loaded into the editor; they are read in chunks.
Choose how to split
By number of lines, number of parts, file size or a line containing a text or regular expression. Optionally repeat the first lines in every part.
Download the parts
Download the ZIP with all parts or single files. Names follow your template, for example orders_part001.csv.
Features
Streaming in a worker
The file is decoded chunk by chunk in a background worker, so a 300 MB log never becomes one huge string and the page stays responsive.
Header in every part
Repeat the first line (or several) at the top of each part, so every piece of a CSV export opens with its column names.
Lines stay whole
Size-based splitting never cuts a line in half; every part ends at a line break and stays under the limit.
Split at a pattern
Start a new file at every line that contains a text or matches a regular expression – for example one file per day in a log or per chapter in a book.
Encoding kept
Parts are written in the encoding of the original file, including UTF-16 and Windows code pages, with its byte order mark.
Limits & privacy
Files up to 500 MB. The parts and the ZIP are kept in memory until you download them, so the browser needs roughly twice the file size of free memory; outputs over 100 MB are zipped without compression to save time. Files above 2 MB are processed without loading them into the editor. Nothing is uploaded. See the privacy page.
FAQ
How do I split a large text file into smaller files?
Open the file, choose Number of lines and set, for example, 100,000 lines per file. Download the ZIP with all parts.
How do I split a CSV file and keep the header?
Set Repeat header lines to 1. The first line of the file is copied to the top of every part and not counted in the lines per file.
Can I split a file into a fixed number of parts?
Choose Number of parts. The file is read once to count its lines, then divided so the parts have the same number of lines.
How do I split by file size?
Choose File size and set the maximum in KB or MB, for example to fit an e-mail attachment or an upload limit.
What are the parts called?
The template {name}_part{n}{ext} gives orders_part001.csv, orders_part002.csv … Change it to any pattern with {name}, {n} and {ext}.