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Diff Checker

Compare two blocks of text and see exactly what changed — instantly. Paste the original and the changed version; added, removed, and unchanged lines are highlighted as you type.

Paste your two texts below, or .

What is a diff checker?

A diff checker compares two texts line by line and highlights what was added, removed, or left unchanged. It’s the fastest way to review an edit, compare two versions of a document, check code changes, or see exactly what a copy-edit touched.

This tool does it entirely in your browser using a line-based longest-common-subsequence comparison — the same approach version-control tools use — so your text never leaves your machine and results appear the moment you paste.

Frequently asked questions

How do I compare two pieces of text?

Paste the original text into the left box and the changed version into the right box. The differences appear instantly below — added lines in green, removed lines in red, unchanged lines in muted text. There's no button to press.

What does a diff checker do?

A diff checker compares two texts line by line and shows what was added, removed, or kept the same. It's used to review edits, spot changes between versions of a document, compare code, or check what a copy-edit changed.

Is my text uploaded anywhere?

No. The comparison runs entirely in your browser with JavaScript. Nothing you paste is sent to a server, so it works offline and keeps your content private.

Is there a size limit?

Each side can hold up to 100,000 characters, which keeps the comparison instant. For larger files, compare them in sections.

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