Code Diff Checker
DataCompare two blocks of text or code side by side. See additions, deletions, and changes highlighted in green and red.
What is a diff checker?
A diff checker compares two texts and highlights the differences between them. Added lines are shown in green, removed lines in red, and unchanged lines in gray. This is the same concept used by Git, GitHub pull requests, and code review tools. A diff checker is essential for comparing API responses, verifying configuration changes, reviewing code modifications, and debugging unexpected output differences between environments.
How to compare code effectively
Paste your original text on the left and the modified version on the right. The tool instantly computes a line-by-line diff and displays the results with color-coded highlighting. Use the "Ignore whitespace" toggle when comparing code that may have been reformatted — this focuses on meaningful content changes rather than indentation differences. The side-by-side view with line numbers makes it easy to pinpoint exactly where changes occurred.
Use cases for code diffing
Compare API responses between staging and production to find discrepancies. Verify that a refactoring did not change output. Review configuration file changes before deploying. Check database migration scripts for unintended modifications. Compare minified and formatted versions of the same code. Validate that a code generator produces the expected output. This tool handles any text format — code, JSON, XML, CSV, plain text, and more.
Frequently Asked Questions
What diff algorithm does this tool use?
This tool uses a longest common subsequence (LCS) algorithm to compute line-level differences. It identifies the minimum set of additions and deletions needed to transform the original text into the modified version, then displays them with color-coded highlighting.
Can I ignore whitespace differences?
Yes. Toggle the "Ignore whitespace" option to treat lines with different indentation or trailing spaces as identical. This is useful when comparing code that has been reformatted or when you only care about content changes, not formatting.
Does this tool work with large files?
Yes. The diff algorithm runs entirely in your browser and handles texts with thousands of lines. For very large files (10,000+ lines), there may be a brief processing delay. No data is sent to any server.
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