Diff Checker
Compare two texts line by line and highlight added and removed lines, using a real LCS diff — entirely in your browser. Free.
Compare two texts
Paste the original and changed text to see a line-by-line diff.
What this diff checker does
Common use cases
- 1Comparing two versions of a file
- 2Reviewing a config change
- 3Spotting an edit in pasted text
- 4Checking a copy revision
- 5Diffing two API responses
- 6Verifying a find-and-replace
Related tools
About diffing
A diff shows what changed between two texts. This tool uses the classic longest-common-subsequence algorithm to find the smallest set of added and removed lines that turns the original into the changed version — the same idea behind git diff.
Added lines are shown in green, removed lines in red, and unchanged lines in grey. Everything is computed in your browser, so even sensitive text never leaves your device.
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Got Questions? We Have Answers.
How does the diff work?
It uses the classic longest-common-subsequence algorithm — the same idea behind git diff — to find the minimal set of added and removed lines.
Is my text uploaded?
No. The comparison runs entirely in your browser, so even sensitive text never leaves your device.
What does it show?
Added lines in green, removed lines in red, unchanged lines in grey, plus a count of each so you can see the scale of changes.
Can I diff code?
Yes. It works on any text — code, config, prose or API responses — comparing line by line.