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Diff Checker

Compare two texts side by side and highlight differences. Find changes between code versions, configs, or any text.

What is a Diff Checker?

A diff checker (or text comparison tool) identifies differences between two blocks of text, highlighting additions, deletions, and changes line by line. It’s an essential tool for developers, writers, and anyone who needs to compare two versions of a document or code file.

Our online diff checker provides a clear visual comparison with color-coded highlighting — red for removed lines and green for added lines. It runs entirely in your browser, so your code and text are never uploaded to any server.

How to Use This Diff Checker

  1. Paste the original text in the left panel
  2. Paste the modified text in the right panel
  3. Click “Compare” to generate the diff
  4. Review highlighted changes — red lines were removed, green lines were added
  5. Use the results to understand exactly what changed between versions

Common Use Cases

  • Code review — Compare two versions of a file to see what changed in a pull request
  • Configuration auditing — Spot differences between staging and production config files
  • Document revision tracking — Compare drafts of contracts, documentation, or content
  • Debugging — Find unintended changes by comparing working and broken versions of code
  • Migration verification — Confirm that data was transferred correctly between systems

Frequently Asked Questions

How does a diff algorithm work?

Most diff tools use variations of the Longest Common Subsequence (LCS) algorithm. It finds the longest sequence of lines that appear in both texts, then marks everything else as additions or deletions. This gives you the smallest possible set of changes.

Can I compare binary files with this tool?

This tool is designed for text comparison. For binary files (images, compiled code), use specialized tools like hexdump with diff, or image comparison tools.