What is a diff checker?

A diff checker is a tool that compares two pieces of text and highlights the differences between them. It uses the Myers diff algorithm — the same algorithm behind Git and other version control systems — to find the minimum set of changes needed to transform one text into the other. Our diff checker runs entirely in your browser, so your data never leaves your device.

Key features

Three comparison levels — Compare at line, word or character level for different levels of granularity
Side-by-side and inline views — Choose the view mode that works best for you. Side-by-side shows both texts next to each other, inline merges them into a single stream
Ignore whitespace — Toggle this option to skip differences caused by spaces, tabs and line endings
Ignore case — Compare texts without regard to uppercase and lowercase letters
Color-coded highlights — Additions are shown in green, deletions in red, making changes easy to spot at a glance
Statistics — See the exact count of additions, deletions and unchanged segments
Swap and copy — Quickly swap the original and modified texts or copy the diff result to your clipboard
100% private — All processing happens in your browser. No text is sent to any server

How to use the diff checker

Paste or type your original text in the left field
Paste or type the modified text in the right field
The diff is computed automatically — differences are highlighted instantly
Use the toolbar to switch between line, word or character comparison
Toggle between side-by-side and inline views to find the one that suits you
Enable 'Ignore whitespace' or 'Ignore case' if needed
Click Copy to copy the diff result or Clear to start over

Use cases

Code review

Compare two versions of source code to see exactly what changed. Perfect for reviewing pull requests, patches and refactoring results.

Document comparison

Spot differences between two versions of a contract, article or report. Useful for legal, editorial and academic work.

Content editing

Compare drafts of blog posts, product descriptions or marketing copy to track changes made during the editing process.

Configuration files

Check differences between server configs, .env files or settings files to quickly find what was added, removed or modified.

Frequently asked questions

Is the diff checker free?

Yes, the diff checker is completely free with no limits, no ads and no registration required. You can use it as many times as you need.

Is my data secure?

Absolutely. All comparison is done locally in your browser using JavaScript. Your text is never sent to any server, ensuring complete privacy and security.

What comparison modes are available?

You can compare at three levels: line-by-line (best for code and structured text), word-by-word (best for prose and documents) and character-by-character (best for finding tiny changes like typos).

Can I compare code with this tool?

Yes, the diff checker works great for comparing code. Use line-level comparison for the most familiar diff view. The monospace font and whitespace-aware comparison make it ideal for code review.

What is the maximum text size?

Since the tool runs in your browser, the limit depends on your device's memory. In practice, it handles texts of 100,000+ characters without issues on modern devices.

Does it work on mobile?

Yes, the diff checker is fully responsive and works on smartphones, tablets and desktop computers. On smaller screens, the inline view mode is recommended for the best experience.

Diff Checker