Text Diff Checker
Compare two texts side by side and see the differences highlighted. Line-by-line diff with additions in green and deletions in red. Supports case-insensitive and whitespace-ignoring comparison.
Compare two blocks of text and see the differences highlighted line by line. Our free text diff checker shows additions, deletions, and unchanged lines in a clear, color-coded view. Supports case-insensitive and whitespace-ignoring comparison. All processing happens in your browser.
Paste text in both boxes to see the diff
or click "Load Sample" to try it out
100% Client-Side Processing
All text comparison happens directly in your browser using a JavaScript diff algorithm. No data is sent to any server. Safe for comparing sensitive code, documents, and configuration files.
How to Use the Text Diff Checker
- Paste the original text in the left textarea.
- Paste the modified text in the right textarea.
- View the diff — additions are shown in green (+), deletions in red (-), and unchanged lines have no highlight.
- Use options — toggle "Ignore whitespace" or "Ignore case" to customize comparison behavior.
- Review stats — the summary shows how many lines were added, removed, and unchanged.
Common Use Cases
Code Review
Compare two versions of source code to see what changed
Document Comparison
Find differences between document drafts or versions
Config Files
Compare configuration files to spot changes in settings
Debug Output
Compare expected vs actual output in test debugging
Content Editing
Track changes in articles, blog posts, or documentation
Data Verification
Compare data exports to verify consistency
Related Tools
Working with text? Try our Word Counter for character and word statistics, our Remove Extra Spaces to clean up text, or our Duplicate Line Remover to find and remove repeated lines.
Frequently Asked Questions
What diff algorithm does this tool use?▼
This tool uses a Longest Common Subsequence (LCS) based diff algorithm, similar to what Git and other version control systems use. It finds the optimal set of changes (additions and deletions) needed to transform the original text into the modified text.
What does "Ignore whitespace" do?▼
When enabled, consecutive spaces and tabs are collapsed to a single space, and trailing whitespace on each line is removed before comparison. This is useful for comparing code with different indentation styles or text from different editors.
Can I compare large files?▼
This tool works well for text up to several thousand lines. Very large files (tens of thousands of lines) may be slow in the browser since the diff algorithm runs in O(n*m) time. For large files, consider using a command-line tool like diff or your IDE's built-in diff viewer.
Is my data safe?▼
Yes. All comparison happens entirely in your browser. Your text is never sent to any server or stored anywhere. You can verify this by disconnecting from the internet — the tool will continue to work normally.
Frequently Asked Questions
❓ Is this tool free?
Yes! All our tools are completely free. No registration, no hidden charges, no ads. Just open and use.
🔒 Is my data safe?
Absolutely. All calculations happen in your browser. We don't store, send, or track any of your data. Everything is processed locally on your device.
📱 Can I use this on mobile?
Yes! All our tools are fully responsive and work perfectly on smartphones, tablets, and desktops.
🌐 Do I need internet?
No! Once the page loads, you can use the tool completely offline. All calculations happen in your browser without any server connection.