Diff Checker

Compare two blocks of text, code, CSV, or JSON side by side. See additions, deletions, and unchanged lines instantly. 100% client-side.

100% Client-SideNo UploadFree ForeverNo Sign-up
Original
Modified

Paste text into both panels and click Compare to see the diff.

How to Use This Diff Checker

Paste your original text into the left panel and the modified version into the right panel, or upload files directly. Click the Compare button to generate a visual diff.

The tool highlights added lines in green and removed lines in red. Unchanged lines appear without color. Use the Side-by-Side view to see both versions aligned next to each other, or switch to Unified view for a compact single-column diff similar to git diff output.

Toggle Ignore Whitespace to skip differences caused by spacing or indentation. Toggle Ignore Case to treat uppercase and lowercase letters as equal. Use Swap to exchange the two panels, and Copy Diff to copy the result in a shareable unified diff format.

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Frequently Asked Questions

You can compare any text-based content including plain text, CSV, JSON, XML, YAML, JavaScript, Python, HTML, CSS, configuration files, and more. Simply paste the text or upload the files.
No. All comparison processing happens 100% in your browser using JavaScript. Your data never leaves your device. There are no uploads, no tracking, and no storage of your content.
The diff checker uses a Longest Common Subsequence (LCS) algorithm to perform line-by-line comparison. It identifies which lines are shared between both texts and which were added or removed, then aligns them for easy visual comparison.
Yes. The diff checker runs entirely in your browser and can handle files with thousands of lines. Performance depends on your device, but most comparisons complete in under a second.
Green highlights indicate lines that were added in the modified text. Red highlights indicate lines that were removed from the original text. Unchanged lines appear without color highlighting.

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