CSS Compare

About the CSS Compare Tool

What is a CSS compare tool?

A CSS compare tool shows you exactly what changed between two stylesheets: every rule that was added or removed, and every declaration whose value moved — with the changed words picked out inside each line, so a color that went from #3b82f6 to #2563eb is highlighted character-for-character. Removed code shows in red on the left, added code in green on the right, with a live tally and similarity score on top.

The trick that makes it work on real-world CSS is the built-in formatter. Both stylesheets are normalized first — one declaration per line, consistent spacing and indentation — so a minified production file compares cleanly against its pretty-printed source instead of showing up as one giant changed line. Flip on Sort declarations and property order stops mattering too, leaving only real changes. Everything runs locally in your browser.

How to Use This Tool

1. Add both stylesheets. Paste the original CSS on the left and the changed version on the right, drag .css files onto the boxes, or use the Open buttons. Sample loads a demo pair.
2. Let the formatter align them. With Format CSS on (the default), both sides are normalized before comparing — minified or messy input is fine.
3. Read the highlights. Red is removed, green is added, and modified declarations show exactly which values changed.
4. Silence order noise. Enable Sort declarations to compare rules property-order-independently, and Only show differences to hide everything unchanged.
5. Export. Copy the result or download it as a .diff file.

Common Use Cases

• Debugging style regressions: Diff the stylesheet from the last working deploy against the current one to find the rule that broke the layout.
• Comparing minified builds: Check what actually changed between two production bundles — the formatter makes minified CSS readable and diffable.
• Reviewing theme edits: See every tweak a designer or plugin made to a theme's CSS.
• Upgrading libraries: Compare two versions of a framework's stylesheet to see what the update really touched.
• Merging styles: Reconcile two diverged copies of a stylesheet by spotting their exact differences.

Cleaning up a single file instead? Use our CSS Formatter or CSS Validator, or compare markup with the HTML Compare tool.

Frequently Asked Questions

Can I compare minified CSS?

Yes, and that is this tool’s specialty. With Format CSS enabled, both stylesheets are expanded to one declaration per line with identical spacing before the diff runs, so a minified file and its readable source compare line for line instead of as one enormous changed row.

Does the order of properties matter?

Only if you want it to. By default the diff is textual, so reordered declarations show as changes. Switch on Sort declarations and the properties inside every rule are alphabetized on both sides first, which makes the comparison order-independent and leaves only genuine value changes.

What does the braces badge mean?

Each pane is checked for balanced curly braces as you type, ignoring braces inside strings and comments. An Unbalanced braces warning usually means a truncated copy-paste or a missing closing brace, which is worth fixing before trusting the comparison.

Will comments and strings confuse the formatter?

No. The formatter is string- and comment-aware: semicolons inside url(data:...) values, braces inside content strings, and /* comments */ are all preserved untouched rather than being treated as structure.

Can I compare SCSS or LESS?

You can paste them, and nesting is indented sensibly since the formatter follows braces. The comparison itself is still textual per line, which works well for most preprocessor files, though @-rule-heavy syntax is compared as written rather than compiled.

Is my CSS private?

Yes. Formatting and comparison run entirely in your browser with JavaScript. Nothing is uploaded, stored, or logged, and the tool works offline once the page has loaded.