Is this diff checker free?

Yes, 100% free with no limits. Compare as many texts as you want — no signup required.

What does the diff checker highlight?

It highlights three types of changes: additions (green), deletions (red), and unchanged lines. You can switch between side-by-side and unified views.

Does my data get sent to any server?

No. All comparison happens in your browser. Your text never leaves your device.

Can I compare code files?

Yes. It works with any text — code, prose, configuration files, CSV data, JSON, or any plain text.

Does it show line numbers?

Yes. Each line shows its line number for easy reference. Change statistics are shown at the top.

✓ Side-by-side✓ Line numbers✓ Free forever

Free Diff Checker — Compare Text Online

Compare two blocks of text side-by-side. Highlights additions, deletions, and changes with line numbers.

Original Text

Changed Text

How to use Diff Checker

Three steps. Instant comparison.

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Paste both texts

Paste the original text on the left and the changed text on the right.

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Click Find Differences

The tool compares line by line and highlights every addition, deletion, and change.

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Review the diff

Switch between side-by-side and unified views. Check the stats for a quick summary.

How Diff Checker works

This tool uses the jsdiff library to perform a line-by-line comparison of two texts. The algorithm finds the longest common subsequence between both inputs, then identifies which lines were added, removed, or stayed the same. Each difference is color-coded — green for additions, red for deletions. The side-by-side view shows the original and changed text in parallel columns, while the unified view shows all changes in a single stream with +/− prefixes. Everything runs in your browser using JavaScript — no data is sent to any server.