Diff Checker

How to use

1. Paste texts — Enter original and modified text
2. View diff — See added and removed lines highlighted
3. Review — Understand exactly what changed

What Is a Diff Checker?

A diff checker compares two text inputs and highlights the differences between them. Lines that were added appear in green, removed lines in red, and unchanged lines are shown normally. It's the same concept behind Git diffs and code review tools.

How It Works

The tool uses the Longest Common Subsequence (LCS) algorithm to find the optimal alignment between the two texts, then marks each line as unchanged, added, or removed. This produces the minimal diff — the smallest set of changes needed to transform the original into the modified version.

Use Cases

• Code review: Compare code versions before and after changes
• Document editing: See what changed between document revisions
• Configuration: Compare config files across environments
• Testing: Compare expected vs actual output

Privacy

All comparison runs in your browser. Your text never leaves your device.

Compare JSON objects with JSON Diff. Test patterns with Regex Tester.

Frequently asked questions

What algorithm is used?

LCS (Longest Common Subsequence) based line-by-line comparison, similar to Unix diff.

Does it support word-level diff?

This tool compares line by line. For word-level differences within lines, use a code editor diff.

Can I compare code?

Yes. It works with any text — code, prose, CSV, configuration files, etc.

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