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Diff Checker

Compares two input texts side-by-side, highlighting inserted, deleted, and changed lines with distinct background colors. Code never leaves your device — formatting and validation run locally in your browser.

Runs on diff-match-patch

100% Local Browser Native

How to Use the Diff Checker

1. Paste both texts

Original in the left pane, revised in the right — full documents are fine.

2. Run the diff

Additions, deletions, and moves highlight line by line.

3. Review every change

Walk each hunk before accepting; whitespace-only diffs can hide real edits.

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Frequently Asked Questions

What types of differences does it highlight?

Insertions (new lines added), deletions (lines removed), and modifications (changed lines) are each highlighted with distinct background colors so you can spot every difference at a glance.

Is there a limit on text size?

There's no hard limit. Very large texts (100KB+) may take a moment to compare, but the diff-match-patch algorithm handles substantial inputs efficiently.

Can I compare code files?

Yes. Paste any text — code, config files, documentation, or plain text. The tool compares line-by-line and highlights exactly what changed between the two versions.

Does it work offline?

Yes. After the initial page load, the comparison runs entirely in your browser using the diff-match-patch library. No data is sent to any server.

Can I copy the diff results?

The highlighted comparison is displayed visually. You can select and copy the text from either panel, or take a screenshot of the side-by-side view.

What does the downloadable diff file contain?

A unified-style text where every line is prefixed + for additions (op 1), - for deletions (op -1) or a space for unchanged context (op 0), split per newline. It downloads as diff.txt from the Comparison Output toolbar.

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Last updated October 2026