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Text Difference Checker

Compare two texts instantly with accurate Myers diff highlighting. Side-by-side view, unified diff, similarity score, and multiple comparison modes.

Updated

What is the Text Difference Checker?

Instantly compare two texts and see exactly what changed.

Text Difference Checker highlights additions, deletions, and modifications with crystal-clear side-by-side visualization. Powered by the reliable Myers diff algorithm, it supports line, word, and character-level comparison with options to ignore case or whitespace.

Whether you're reviewing documents, comparing code versions, proofreading articles, or tracking contract changes, this tool gives you professional-grade diff capabilities completely in your browser — fast, private, and free.

How it works

  1. Paste your texts — Enter the original text on the left and the modified version on the right.

  2. Choose comparison options — Select Lines, Words, or Characters mode. Enable Ignore Case or Ignore Whitespace as needed.

  3. Live comparison — Results update instantly using the Myers diff algorithm.

  4. Review highlights — Red shows removed content, green shows added content. Side-by-side panels make changes easy to scan.

  5. Analyze stats — View added/removed counts, changed items, and overall similarity percentage.

  6. Get unified diff — Copy the standard unified diff format for use in git, emails, or documentation.

Examples

Article Revision

Compare original and edited versions of a blog post.

The quick brown fox jumps over the lazy dog.
This is an important feature.
The quick brown fox jumps over the lazy dog.
This is a critical new feature.

Code Review

Spot changes between two versions of a function.

function calculateTotal(items) {
  return items.reduce((sum, item) => sum + item.price, 0);
}
function calculateTotal(items, taxRate = 0) {
  const subtotal = items.reduce((sum, item) => sum + item.price, 0);
  return subtotal * (1 + taxRate);
}

Frequently asked questions

What is a text difference checker?

A text difference checker (or diff tool) compares two pieces of text and highlights additions, deletions, and modifications. It helps writers, developers, students, and editors quickly identify changes between versions.

How accurate is the diff algorithm?

This tool uses the efficient Myers diff algorithm (shortest edit script) for precise line, word, or character-level comparisons. It is more accurate than simple string matching used by many basic online tools.

Does it work offline?

Yes. All processing happens in your browser. No data is sent to any server, ensuring complete privacy.

What comparison modes are available?

  • Lines: Best for documents and paragraphs.
  • Words: Ideal for sentence-level changes.
  • Characters: Most detailed, perfect for code or precise editing.

Can I ignore case or whitespace?

Yes. Toggle "Ignore case" and "Ignore whitespace" options to focus on meaningful differences and reduce noise.

What is the similarity score?

It shows a percentage (0-100%) indicating how similar the two texts are, based on the number of matching vs. changed tokens.

How do I copy the results?

Use the built-in Copy buttons for the unified diff or share the highlighted comparison visually.

Is there a limit on text size?

The tool handles thousands of lines efficiently thanks to the optimized Myers algorithm. Very large documents may be slower on older devices.

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