Paste the original on the left and the changed version on the right. Added lines are green, removed lines red, and unchanged lines keep their numbers so you can find them in your editor.
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The tool finds the longest common subsequence of lines between the two texts, the same idea behind git diff. Lines in the original that don't appear in the same order in the new version are shown as removed, and new lines as added. Identical lines at the start and end are skipped first, so even long documents with a small change compare instantly.
Ignore whitespace to see past re-indentation or trailing spaces, ignore case to compare configuration where capitalisation doesn't matter, and 'show only changes' to hide the unchanged lines. Copy as unified diff gives you a +/- patch-style output to paste into a ticket or code review comment.
📖 Read the full guide: How Text Diff Works and How to Read One
Compare two JSON documents and see every added, removed and changed value by path.
Format, validate, minify and syntax-highlight JSON — with exact error line and column.
Minify or beautify JavaScript, CSS, HTML and JSON — see the size you saved.
Test JavaScript regular expressions live — highlighted matches, capture groups and replace preview.
Lines. It is ideal for code, configs, logs and lists. For prose, put each sentence on its own line first, or use the JSON Compare tool for structured data.
Comparisons up to several thousand lines per side run instantly. If two very large texts are almost entirely different, the tool asks you to trim them.
No. It is processed in your browser and never sent anywhere.