Diff Checker
Compare two texts side by side and instantly see additions, deletions, and unchanged lines. Powered by the LCS algorithm, entirely client-side.
What is a Diff Checker?
A diff checker is a tool that compares two blocks of text and highlights the differences between them. It is essential for developers reviewing code changes, writers tracking document revisions, and anyone who needs to spot exactly what changed between two versions of a file.
Our free online diff checker uses the Longest Common Subsequence (LCS) algorithm to produce accurate, line-by-line comparisons. Everything runs in your browser, so your text is never uploaded or stored on any server. Use it for code reviews, content edits, configuration changes, or any text comparison task.
Track Changes
Instantly see every addition and deletion between two document versions. Never miss an edit again.
Review Code
Compare code files line by line with syntax-friendly monospace output and clear color coding.
Compare Content
Check blog posts, articles, or marketing copy for revisions. Keep your content workflow organized.
How to Use
Paste Your Texts
Paste the original text on the left and the modified text on the right. You can also type directly into either field.
Click Compare
Hit the Compare button to run the LCS diff algorithm. The tool processes everything instantly in your browser.
Review the Diff
See additions in green, deletions in red, and unchanged lines in white. Toggle between unified and side-by-side views.
Frequently Asked Questions
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