Sentence Splitter
Split any text into one sentence per line. The rule-based detector keeps abbreviations, initials, decimals, list markers and quoted speech from breaking a sentence in the wrong place. Numbered, blank-line-separated or JSON output with word and character counts. Runs entirely in your browser, no upload, no sign-up.
About this tool
Sentence Splitter breaks a block of text into its individual sentences — one per line, ready to paste into a spreadsheet, a translation memory, a subtitle file, or a review pass over a long document.
Splitting on every . gets it wrong almost immediately. This tool uses a
rule-based boundary detector that leaves these alone:
- Titles and abbreviations —
Dr.,Mrs.,Prof.,e.g.,i.e.,vs.,No. 5 - Initials —
J. R. R. Tolkien - Decimals, money and versions —
3.14,$99.99,1.2.3 - List markers —
1. Buy milkstays with its item - Ellipses and quoted speech —
Wait... really?,"Stop!" he said.
A period followed by a lowercase word is treated as mid-sentence, and the
full-width terminators 。, ！ and ？ are recognised too.
Worked example — paste this in:
Dr. Green paid $99.99 for it. It arrived on Mar. 3 and works fine.
and with the default settings you get:
Dr. Green paid $99.99 for it.
It arrived on Mar. 3 and works fine.
Output format picks how the list is rendered: one sentence per line,
a numbered list, a blank line between sentences, or JSON — which adds a total
count plus an index, words and characters figure per sentence.
Line breaks decides what a newline means in your input. Only a blank line ends a sentence (the default) is right for wrapped prose. Never end a sentence joins hard-wrapped lines back together and relies on punctuation
alone. Always end a sentence treats every line as its own sentence, which is
what you want for lists, subtitle cues, and text with no punctuation at all.
Minimum sentence length drops fragments shorter than the given number of
characters, and Extra abbreviations lets you add your own never-split
terms — handy for company suffixes (Corp., Ltd.) or a domain's jargon.
Everything runs locally in your browser as WebAssembly: your text is never uploaded. Input is capped at 500,000 characters and the minimum-length filter at 10,000.
FAQ
How does it know that "Dr." is not the end of a sentence?
It carries a built-in list of titles and abbreviations that never end a
sentence (Mr., Mrs., Dr., Prof., Rev., e.g., i.e., cf., vs.
and more), plus a second list that only suppresses a break when a number
follows (No. 5, Fig. 2, Vol. 3, Ch. 7). On top of that, a period
between two digits is never a boundary, a single letter before a period is
read as an initial, and a lowercase word after any terminator means the
sentence is still going.
My text uses an abbreviation the tool splits on. Can I fix it?
Yes — put it in Extra abbreviations. Entries can be separated by commas,
semicolons or spaces, the trailing period is optional, and matching is
case-insensitive, so Corp., Ltd, Inc. all work. They are merged into the
built-in never-split list for that run.
What is the difference between the three line-break modes?
Only a blank line ends a sentence (default) treats a single newline as a
space and a blank line as a hard break — correct for normal paragraphs.
Never end a sentence ignores newlines entirely, so hard-wrapped text is
rejoined and only punctuation splits it. Always end a sentence breaks on
every newline, which is the right choice for bullet lists, subtitle cues, or
any text where each line is already one sentence.
Does it use an AI model?
No. It is a deterministic rule-based detector compiled to WebAssembly, so the same input always produces exactly the same output, offline and instantly. The trade-off is that a genuinely ambiguous case — an unknown abbreviation followed by a capitalised word — can still be split in the wrong place. Adding that abbreviation to Extra abbreviations fixes it.
Can I get sentence and word counts?
Choose the JSON output format. You get {"count": N, "sentences": [...]}
where each sentence carries its 1-based index, the text, a words count
(whitespace-separated) and a characters count (Unicode characters).
Does it work on languages other than English?
Partly. The abbreviation lists are English, but the core rules — terminator
runs, closing quotes and brackets, decimals, lowercase continuation — apply to
any Latin-script text, and the full-width terminators 。, ！ and ？ used
in Chinese and Japanese are split correctly without needing a following space.
Languages whose sentence boundaries do not rely on those marks are out of
scope.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool sentence-split 'Dr. Green paid $99.99 for it. It arrived on Mar. 3 and works fine.'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/sentence-split/?text=Dr.%20Green%20paid%20%2499.99%20for%20it.%20It%20arrived%20on%20Mar.%203%20and%20works%20fine.&format=lines&newlines=paragraph&trim=true&min_chars=0&extra_abbreviations=Corp.%2C%20Ltd.%2C%20Inc.Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.