Free Online Text Diff Checker

Compare two pieces of text or code side by side with additions in green and removals in red. Accurate LCS diff, downloadable results, 100% private.

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Compare Text Side by Side with Accurate Diff Highlighting

Our free online text diff checker uses a Longest Common Subsequence (LCS) algorithm to compare two text passages line by line, highlighting additions in green and removals in red. Everything runs in your browser — no uploads, no server processing, and your text stays completely private. Download the result as a unified diff file for version control, code reviews, or document comparison workflows.

Why Use Our Text Diff Checker?

  • Precise LCS algorithm: Industry-standard diff algorithm accurately identifies changes down to the line level.
  • Side-by-side visual diff: See additions (green) and deletions (red) instantly with synchronized scrolling.
  • 100% private & offline: Your code, documents, and config files never leave your browser.
  • Downloadable unified diff: Export results as a standard .txt patch file for Git, code reviews, or archival.

How to Compare Text

  1. Paste the original text in the left panel and the modified text in the right panel.
  2. Click Compare — the diff highlights changes instantly with color-coded lines.
  3. Review additions and removals with synchronized line-by-line scrolling.
  4. Download the unified diff .txt file or copy results for your workflow.

Working with PDFs? Extract text first using our PDF to Text tool, then compare versions. For word count analysis on extracted text, try the PDF Word Count tool.

Frequently Asked Questions

How does the diff checker work?

It uses a Longest Common Subsequence (LCS) algorithm to compare lines and highlight additions and deletions accurately.

Can I download the diff result?

Yes. Download the result as a unified diff .txt file to share or archive.

Is my text private?

Yes. Comparison happens entirely client-side — your text is never uploaded to any server.

What can I compare?

Any text: source code, documents, configuration files, markup — anything you can paste into the panels.

Is the diff checker free?

Yes, it is completely free with no limits, accounts, or watermarks.