Text Diff Checker

Compare two texts and find differences. See added (green), removed (red), and unchanged (gray) lines with change statistics. Perfect for code reviews and document version comparison.

Added: 7 Removed: 3 Same: 8
function greet(name) {
- console.log("Hello, " + name);
+ console.log("Hi, " + name);
}
⏎
function calculateTotal(items) {
let total = 0;
- for (let i = 0; i < items.length; i++) {
+ for (const item of items) {
- total += items[i].price;
+ total += item.price;
}
return total;
}
+⏎
+function formatCurrency(amount) {
+ return "$" + amount.toFixed(2);
+}

About Text Diff Comparison

Text diff comparison is a fundamental tool for developers and writers. It helps you track changes between versions of code, documents, or any text. By comparing the original and modified versions line by line, you can quickly identify what was added, removed, or changed. This is especially useful for code reviews, where you need to verify that changes are correct before merging.

Common Use Cases

  • Code Review: Review pull request changes before merging
  • Version Tracking: Compare different versions of configuration files
  • Document Editing: Track edits in documents and articles
  • Debugging: Compare working vs non-working code to find bugs
  • Data Validation: Compare CSV exports or data dumps for discrepancies

Frequently Asked Questions

How does the diff checker work?
The diff checker compares two texts line by line. Lines that are identical in both texts are shown as unchanged (gray). Lines that appear in the original but not in the new text are shown as removed (red). Lines that appear in the new text but not in the original are shown as added (green). The tool also shows a summary of total changes.
What types of files can I compare?
You can compare any text-based content including: source code (JavaScript, Python, HTML, CSS, etc.), configuration files (JSON, YAML, XML), documents (Markdown, plain text), CSV/TSV data, and any other text format. The tool works line-by-line, so it's best for comparing structured text with clear line boundaries.
Is this diff tool secure for sensitive code?
Yes. All diff comparison happens entirely in your browser. Your text is never sent to any server. This makes it safe for comparing proprietary code, sensitive documents, or confidential data. No data leaves your computer.
What is the difference between unified and side-by-side diff?
This tool uses a side-by-side line comparison showing all lines in sequence. Traditional 'unified diff' format shows only changed lines with context markers. Side-by-side is more visual and easier to read for most users. For command-line use, `git diff` uses the unified format by default.
Can I compare large files?
The tool works best with files up to a few thousand lines. Since processing is done in the browser, very large files (10,000+ lines) may cause performance issues. For large file comparison, consider using command-line tools like `diff` or `git diff` which are optimized for large files.
What does 'same', 'added', and 'removed' mean?
'Same' lines are identical in both texts — no changes made. 'Added' lines exist only in the new text — these are insertions. 'Removed' lines exist only in the original text — these are deletions. For example, if you added a new function in version 2, all its lines would show as 'added'.

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