Text diff checker
Paste two versions of any text and this diff checker lines them up side by side, with every added, removed and changed line highlighted. The comparison uses the same line-matching approach as command-line diff tools, and it runs entirely in your browser.
- Nothing you type leaves this page
- Works offline once loaded
- Free forever, no signup
Preparing Text Diff Checker for you…
Loading the tool into your browser. Nothing is uploaded — the work happens on your device.
No differences found — the two texts are identical.
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How to use this tool
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Paste the original text on the left
And the changed version on the right, or load the sample to see it in action.
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Read the highlighted comparison
Removed lines are marked in red, added lines in green, and changed lines show both versions side by side.
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Copy the result
Copy diff gives you a plain-text +/- summary you can paste elsewhere.
Questions people ask
How does this tool decide which lines match?
It finds the longest common subsequence of lines between the two texts — the same technique behind git diff — so it aligns unchanged lines correctly even when several lines were inserted or deleted in between.
Can I compare very long documents?
Yes, though above roughly 2,000 lines on either side the tool switches to a faster line-by-line comparison instead of the full alignment, so the tab never freezes. A note appears on screen whenever that happens.
Can I ignore case or whitespace differences?
Yes — the ignore case and ignore whitespace toggles fold those differences away before comparing, which is useful when only the wording matters, not formatting.
What does a "changed" line mean versus "removed" and "added"?
When a removed line is immediately followed by an added line, the tool shows them together as one changed row so you can read the before and after in place, rather than as two separate one-sided edits.
Is it safe to compare confidential text here?
Yes — the comparison runs entirely in your browser's JavaScript. There is no upload endpoint on this page at all, so contracts, code and private drafts never leave your device.
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Bookmark this page — the tool keeps working offline, and your settings stay in this browser. Built by Dynamb Technologies, who make software for a living.