Can I split a text file by lines?

Choose Lines and enter how many existing lines belong in each chunk. Open a UTF-8 file or paste text. CRLF, LF and CR endings are kept with their lines; the selected chunk can be copied or saved. The line mode does not wrap a long sentence into new lines or understand quoted multiline CSV records.

How do I split a text file into smaller files?

Open the file with the Open file button or drop it on the panel, choose what to count, type a chunk size, and the pieces are listed in the chunks pane as you go. Each piece is a file in waiting: chunk-01.txt, chunk-02.txt and so on, numbered to the width of the count so they stay in order in any file list, and named after your file once you open one. Pick a piece in the list and Copy puts it on the clipboard or Save writes it out as a .txt file. There is no zip download, so the files come out one at a time, which is the trade for never uploading anything.

Do the chunks really join back into the original?

Yes, in all five modes when overlap is zero. Lines retain their original endings, words retain spacing and punctuation, and delimiters stay at the end of the pieces they close. Concatenate the chunk text directly, without adding separators. File import validates UTF-8 and preserves a leading BOM; it refuses malformed byte sequences instead of replacing them.

How much text can it split at once?

Up to 2,000,000 grapheme characters and 2,000 chunks in one pass. Larger requests are refused without truncation. Files must contain valid UTF-8 text; convert another encoding in a text editor first. Each saved file is UTF-8 text. Plain splitting does not guarantee that chunks of CSV, JSON, Markdown or subtitles are independently valid documents.

Can I split a CSV or subtitle file this way?

The tool reads it as plain UTF-8 text. It preserves existing lines but does not keep quoted multiline CSV records, repeated headers, subtitle cues or JSON objects intact. Chunks may need format-specific processing before another program can open them independently.

Text File Splitter by Lines

Split pasted text or a UTF-8 file into chunks of existing lines. This page opens in Lines mode with 500 lines per chunk and zero overlap. Each line retains its original CRLF, LF or CR ending, and each chunk receives an ordered filename. Select a chunk to copy or save it as TXT. Line splitting does not wrap sentences or parse file structures.

input.txt48,120 chars, 48,824 bytes

The quick brown fox jumps over the lazy dog. Every chunk here ends on a character boundary, so nothing arrives as a question mark in a box. The text never leaves this tab, which matters when the transcript is a client call. A chunk is only useful when it ends where you meant it to end. A model with a context window does not care where your paragraph ended, but you might. Numbering the pieces is half the job: chunk 01 comes before chunk 02 in every file list.

Paste a long transcript, pick a size, and read the pieces back in order. An overlap carries the end of one chunk into the start of the next, so a sentence cut in two is readable in both. Résumé, jalapeño and Köln each carry a letter that costs two bytes. The café menu, the naïve regex and the flag 🇫🇷 are one character each to a reader. Line mode keeps original line endings; structured records need separate checks. The splitter counts what you can see, not what the encoder happens to store. 📄

Counting by code unit is what turns one emoji into two broken halves. Three dashes are enough to cut a screenplay into scenes. The quick brown fox jumps over the lazy dog. Every chunk here ends on a character boundary, so nothing arrives as a question mark in a box. The text never leaves this tab, which matters when the transcript is a client call. A chunk is only useful when it ends where you meant it to end.

A model with a context window does not care where your paragraph ended, but you might. Numbering the pieces is half the job: chunk 01 comes before chunk 02 in every file list. Paste a long transcript, pick a size, and read the pieces back in order. An overlap carries the end of one chunk into the start of the next, so a sentence cut in two is readable in both. Résumé, jalapeño and Köln each carry a letter that costs two bytes. The café menu, the naïve regex and the flag 🇫🇷 are one character each to a reader.

Line mode keeps original line endings; structured records need separate checks. The splitter counts what you can see, not what the encoder happens to store. 📄 Counting by code unit is what turns one emoji into two broken halves. Three dashes are enough to cut a screenplay into scenes. The quick brown fox jumps over the lazy dog. Every chunk here ends on a character boundary, so nothing arrives as a question mark in a box.

The text never leaves this tab, which matters when the transcript is a client call. A chunk is only useful when it ends where you meant it to end. A model with a context window does not care where your paragraph ended, but you might. Numbering the pieces is half the job: chunk 01 comes before chunk 02 in every file list. Paste a long transcript, pick a size, and read the pieces back in order. An overlap carries the end of one chunk into the start of the next, so a sentence cut in two is readable in both.

Résumé, jalapeño and Köln each carry a letter that costs two bytes. The café menu, the naïve regex and the flag 🇫🇷 are one character each to a reader. Line mode keeps original line endings; structured records need separate checks. The splitter counts what you can see, not what the encoder happens to store. 📄 Counting by code unit is what turns one emoji into two broken halves. Three dashes are enough to cut a screenplay into scenes.

The text never leaves this tab, which matters when the transcript is a client call. A chun...

chunks1 file

The quick brown fox jumps over the lazy dog. Every chunk here ends on a character boundary, so n...

Chunks

Split by

Lines per chunk

lines

Overlap

lines

Last chunk

207 lines

1 chunk of up to 500 lines, no overlap. The last one is 207 lines.

Whole existing lines, each keeping the ending it arrived with. Copy and Save work on chunk-01.txt, the chunk selected in the list.

48,120 chars at 4,000 eachno overlap
13 chunks, the last is 120 characters
Boundary lands mid-charactera 25-byte emoji at a 40-byte budget
26 bytes in the first chunk, not 40: the emoji stays whole
Overlap 200 on 4,000carry-over
13 chunks, each repeating the previous 200 characters

What a chunk boundary can and cannot land on. Wherever this tool picks the boundary, by characters, by bytes, by lines or by words, it picks a grapheme cluster edge, the unit a reader calls a character, so the cut never falls inside an emoji, a skin tone, a flag, a keycap, a combining accent or a surrogate pair. In byte mode that means a chunk stops short of its budget rather than cutting a character: the sample this page opens with is 48,120 characters and 48,824 bytes as UTF-8, and the two numbers move apart exactly where the text stops being ASCII. A delimiter cut is yours to place, and it falls exactly where your delimiter does. Lines keep the ending they arrived with, and a delimiter stays at the end of the piece it closed, which is what lets the chunks add back up to the text they came from.

Up to 2,000,000 characters in one pass and up to 2,000 chunks, read and split here in your browser with nothing uploaded and no account. A delimiter may be typed with the usual escapes, so a blank line is \n\n and a tab is \t. The mode, the size, the overlap, the delimiter and the draft are kept in this browser alone, drafts up to 200,000 characters, and the Start over button above the tool forgets them.

Accuracy. Splitting is exact and reversible: join the chunks back in order with the overlap off and you get the original text back character for character, in every mode. Where this tool picks the boundary, by characters, by bytes or by lines or by words, the cut falls on a Unicode grapheme cluster edge (UAX#29), so it never lands inside an emoji, a combining mark or a surrogate pair, and a chunk stops short of a byte budget rather than breaking a character; a cut at a delimiter falls exactly where you put it, and an overlap must be smaller than the chunk or it is refused. The text is read and split in your browser.

Common questions

Can I split a text file by lines?: Choose Lines and enter how many existing lines belong in each chunk. Open a UTF-8 file or paste text. CRLF, LF and CR endings are kept with their lines; the selected chunk can be copied or saved. The line mode does not wrap a long sentence into new lines or understand quoted multiline CSV records.
How do I split a text file into smaller files?: Open the file with the Open file button or drop it on the panel, choose what to count, type a chunk size, and the pieces are listed in the chunks pane as you go. Each piece is a file in waiting: chunk-01.txt, chunk-02.txt and so on, numbered to the width of the count so they stay in order in any file list, and named after your file once you open one. Pick a piece in the list and Copy puts it on the clipboard or Save writes it out as a .txt file. There is no zip download, so the files come out one at a time, which is the trade for never uploading anything.
Do the chunks really join back into the original?: Yes, in all five modes when overlap is zero. Lines retain their original endings, words retain spacing and punctuation, and delimiters stay at the end of the pieces they close. Concatenate the chunk text directly, without adding separators. File import validates UTF-8 and preserves a leading BOM; it refuses malformed byte sequences instead of replacing them.
How much text can it split at once?: Up to 2,000,000 grapheme characters and 2,000 chunks in one pass. Larger requests are refused without truncation. Files must contain valid UTF-8 text; convert another encoding in a text editor first. Each saved file is UTF-8 text. Plain splitting does not guarantee that chunks of CSV, JSON, Markdown or subtitles are independently valid documents.
Can I split a CSV or subtitle file this way?: The tool reads it as plain UTF-8 text. It preserves existing lines but does not keep quoted multiline CSV records, repeated headers, subtitle cues or JSON objects intact. Chunks may need format-specific processing before another program can open them independently.

Splitting is exact and reversible: join the chunks back in order with the overlap off and you get the original text back character for character, in every mode. Where this tool picks the boundary, by characters, by bytes or by lines or by words, the cut falls on a Unicode grapheme cluster edge (UAX#29), so it never lands inside an emoji, a combining mark or a surrogate pair, and a chunk stops short of a byte budget rather than breaking a character; a cut at a delimiter falls exactly where you put it, and an overlap must be smaller than the chunk or it is refused. The text is read and split in your browser.