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Diff Checker

Compare two texts side by side and highlight differences. Perfect for reviewing code changes, comparing configurations, and tracking document revisions.

Side-by-side diff viewUnified/inline diff viewLine-by-line comparisonAdded/removed highlightingDiff statisticsSwap & clear controls

How to Use the Diff Checker

  1. 1Paste your original text in the left textarea and the modified text in the right textarea
  2. 2The diff is computed automatically — additions, deletions, and unchanged lines are highlighted
  3. 3Switch between Side by Side and Unified view modes using the toggle buttons
  4. 4Review the stats bar showing lines added, removed, and unchanged
  5. 5Use the Swap button to reverse original and modified, or Clear to start over

Frequently Asked Questions

How does the diff algorithm work?

The tool uses a line-based Longest Common Subsequence (LCS) algorithm to find the optimal set of changes between two texts. It identifies which lines were added, removed, or stayed the same, producing a minimal and accurate diff.

What is the difference between side-by-side and unified view?

Side-by-side view shows the original and modified texts in two columns, making it easy to compare corresponding lines. Unified view shows all changes in a single column with + and - prefixes, similar to the output of the Unix diff command.

Can I compare code files with this tool?

Yes! The diff checker works with any text including source code, configuration files, JSON, XML, and more. It preserves whitespace and formatting, so you can accurately compare code changes.

Is my data sent to a server?

No. The diff checker runs entirely in your browser. Your text is never transmitted to any server, ensuring complete privacy and security for sensitive content.

Is there a size limit for the texts I can compare?

There is no hard limit, but very large texts (tens of thousands of lines) may slow down the browser since the LCS algorithm runs client-side. For typical use cases like comparing code files or configuration changes, performance is excellent.

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