Diff Checker
Compare two text blocks and review added, removed, and unchanged lines.
About Diff Checker
A diff makes changes visible by comparing two versions of text. This line-based checker is helpful for reviewing small configuration edits, snippets, and notes without sending either version to a comparison service.
The output preserves line order and marks additions and removals using a longest-common-subsequence comparison. Extremely large comparisons are capped to keep browser memory and processing bounded; for source-code reviews, prefer a version-control diff that also understands files and context.
How to use this tool
Paste the original text on the left and the revised text on the right, then select Compare. Added lines are marked with +, removed lines with −, and unchanged lines with a space.
Frequently asked questions
Does this compare text character by character?
No. It compares complete lines and presents inserted, removed, and unchanged lines in order.
Why is there a size limit?
The comparison uses a longest-common-subsequence matrix whose memory grows with both input lengths. A bounded input size helps keep the browser responsive.
Are blank lines significant?
Yes. Line breaks and blank lines are part of the text and can appear as additions, removals, or unchanged lines in the comparison.
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