Text Diff Checker
Free text diff tool.
Compare two pieces of text and see exactly what changed. Paste an original and a revised version, and the checker highlights every added and removed line so differences jump out instead of hiding in a wall of text. It's ideal for spotting edits between drafts, config files, contracts, or any two versions of the same content.
How the comparison works
The tool compares your two texts line by line and works out the shortest set of changes that turns the first into the second. Each line is then labelled: unchanged lines appear plain, removed lines are marked in red, and added lines in green. Rather than just flagging that "something is different," this shows you precisely which lines were inserted, which were deleted, and which stayed put — the same approach version-control systems use to review changes. For edited lines, you'll see the old version removed and the new version added, which makes even small wording tweaks obvious.
Everything stays in your browser
Because the comparison runs locally, you can safely diff sensitive material — contract drafts, private notes, code, or configuration — without any of it being uploaded. Nothing you paste leaves your device. That makes this a practical everyday tool for writers checking revisions, developers eyeballing a quick change outside their editor, and anyone who needs to confirm what actually changed between two versions of a document before signing off on it.
Common uses for a diff
Comparing two versions of text is useful far beyond programming. Writers check what an editor changed between drafts. Legal and business users compare two versions of a contract or policy to spot every altered clause before signing. Students and researchers confirm what moved between revisions of a document. Anyone copying configuration or settings between two systems can verify the two are identical — or see exactly where they diverge. Because the comparison is line by line and runs entirely in your browser, it's a quick, private way to answer the everyday question "what actually changed here?" without special software.
Line diffing and how to read the result
This checker compares text line by line, which is how version-control systems and most review tools work. Each line is classified as unchanged, added, or removed, and a moved paragraph typically shows up as a removal in one place and an addition in another rather than a "move." That's expected. To get the cleanest comparison, make sure both sides use the same line breaks — pasting from a PDF or a chat app can introduce hidden wrapping that makes matching lines look different. For prose, comparing sentence by sentence (one sentence per line) often reads more clearly than comparing whole paragraphs.
Frequently asked questions
Does it compare word by word or line by line?
Line by line. Each line is treated as a unit, so a changed line shows as the old line removed and the new line added.
Is there a size limit?
Only your device's memory. Because it runs in the browser, there's no upload limit, though very large texts take longer to process.
Is my text uploaded anywhere?
No. The comparison happens entirely in your browser and nothing is sent to a server.
Can it ignore whitespace or capitalisation?
This version compares lines exactly, so differences in spacing or case show as changes. Normalise your text first (for example, lowercase it) if you want to ignore those.
Last updated: 2026-01-20