Text Compare
Find what changed between two versions, word by word or line by line. Neither version leaves your browser.
Paste text into both boxes to see what changed.
Word mode or line mode
The two modes answer different questions, and picking the wrong one is the usual reason a comparison looks useless.
| Mode | Compares | Right for |
|---|---|---|
| Word by word | The running text, ignoring where lines break | Prose, articles, contracts, anything that reflows when edited |
| Line by line | Each line as a single unit | Code, configuration, CSV, lists where the line itself is meaningful |
The distinction matters most with prose. Change one word in the first sentence of a wrapped paragraph and every line after it shifts, so line mode reports the whole paragraph as changed while word mode highlights the single word you actually edited. For code the opposite is true: a line is a real unit, and knowing which lines moved is exactly the point.
What the ignore options change
They relax what counts as the same without altering what is displayed. Ignore case treats Hello and hello as identical. Ignore whitespace collapses runs of spaces and trims the ends of lines, which clears the noise out of a comparison where indentation changed but nothing else did. Ignore punctuation drops marks before matching, which is useful when a draft has been through a copy edit that only moved commas around. In every case the text you see is your original; only the matching is loosened.
How the comparison works
The tool finds the longest sequence of items that appears in both versions in the same order, then reports everything outside that sequence as either removed or added. This is the same approach behind the diff in version control, and it is why the result reads as a sensible set of edits rather than as a character-by-character mess.
The cost of that grows with the length of both sides multiplied together, which is fine for documents and slow for books. Beyond roughly fifteen hundred lines a side the tool says so rather than locking up the page. Comparing section by section is the practical way round it, and usually more readable anyway.
Nothing is uploaded
This deserves saying plainly because of what people compare. Contracts, unpublished drafts, medical letters, private code: all of it commonly gets pasted into an online comparison tool. Here both versions stay in the browser tab. There is no backend to receive them, no request is made when you type, and nothing is stored between visits. Close the tab and it is gone.
How to use it
Paste one version into each box and the differences appear underneath as you type. Swap sides exchanges the two, which flips every addition into a deletion and is a quick way to read the change from the other direction. Copy differences puts a plain-text summary on your clipboard, with removals marked [-like this-] and additions {+like this+}.
Questions
Is my text uploaded to compare it?
No. The comparison runs inside your browser and this tool has no backend, so neither version is transmitted, logged or stored. That is worth knowing before pasting a contract, a draft or anything else you would not put on a stranger's server.
What is the difference between line mode and word mode?
Line mode treats each line as a unit, which suits code, lists and anything with real line structure. Word mode ignores line breaks and compares the running text, which suits prose where a single edit reflows a whole paragraph and would otherwise mark every following line as changed.
Why is a whole paragraph marked as changed when I only edited one word?
That is line mode working as intended: the line differs, so the line is marked. Switch to word mode and only the words that actually changed are highlighted, which is almost always what you want for prose.
Can it compare very large documents?
Up to a point. The comparison cost grows with the two lengths multiplied together, so very large inputs are slow. Beyond roughly fifteen hundred lines a side the tool says so rather than freezing the page, and splitting the documents into sections is the practical answer.
What do the ignore options do?
They change what counts as the same. Ignoring case treats Hello and hello as identical, ignoring whitespace collapses runs of spaces and trims each line, and ignoring punctuation drops marks before comparing. The text shown is always your original; only the matching is relaxed.
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