Text Diff
Compare two versions and see every word that changed, not every line.
Free, no signup, no limits
Original
Changed
Most threads faildie on the first post.line.
Not because the idea is weak,bad, but because the opening line asks the reader to invest before it has givenoffered them anything.anything in return.
The fix is boring. Write the last post first, then cut everything above it.it that is not earning its place.
How to compare two texts
Paste the original on the left and the new version on the right. The differences appear underneath as you type: struck through where something was removed, highlighted where something was added.
Nothing to configure, and nothing leaves the page.
Why word by word matters
Because prose is not made of lines.
Change one word in a paragraph and a line-based diff, which is what most comparison tools and every version control system uses, marks the entire paragraph as removed and the entire paragraph as added. You get two walls of colour and the job of spotting which word moved. On a rewritten page that is worse than useless.
A word diff marks the word. On the same paragraph you see "weak" struck through and "bad" highlighted, and nothing else changes colour.
What it does not do
It does not detect moves. A paragraph shifted from the top of the document to the bottom shows as removed in one place and added in the other, which is accurate and reads as two changes.
That is a limitation of this whole family of algorithms, not of this one in particular. Your editor's diff has it too, and so does the one on your pull requests.
What happens with a long document
It switches to comparing by line, and says so above the result.
Comparing word by word means building a table with every word of one text along one edge and every word of the other along the other. Two thousand words each side is four million cells, which is fine. Twenty thousand each side is four hundred million, which is not.
Two things keep that rare. Identical runs at the start and end of the two texts are matched and set aside before the table is built, so two drafts of the same page only ever compare the part in the middle that differs. Most real edits never come close to the cap.
Nothing is uploaded, which is the point
Text comparison is one of the few things people do with tools like this on documents they are not allowed to share. Two versions of a contract, a policy before and after legal review, a client draft.
Every comparison here happens in the page you are already looking at. There is no server, so there is nothing to trust and no retention policy to read.
What is worth checking alongside
If the two versions came from different places, some of the differences may be invisible ones. A curly quote against a straight quote counts as a change, and so does a non-breaking space, which is a confusing thing to see highlighted when both words look identical. Run both through the AI text cleaner first and those stop appearing.
The word counter is the one for how much the length actually changed, rather than how many edits there were.
Frequently asked questions
More Text tools
Everything else in the Text toolbox.
Something missing here?
If this tool almost does what you need, say what is missing. That is usually how the next version gets built.