CSS Cleaner
CSS Cleaner & Optimizer
What This Tool Does
This tool produces smaller, cleaner CSS without duplicate rules or selectors. It analyzes your stylesheet and consolidates redundant definitions while preserving CSS cascade order. When a selector is defined multiple times, the last rule wins (just like standard CSS), but the output will define everything only once in the proper order.
The result is exactly what you had before, but with a smaller file size and code that's dramatically easier to maintain.
Why Use This Tool?
- Reduces page size - Smaller CSS files mean faster page loads and improved Core Web Vitals
- Improves developer efficiency - Clean, organized CSS helps developers find what they need and make edits faster
- Eliminates technical debt - Perfect for stylesheets that have grown organically over time with multiple developers
- Consolidates scattered media queries - Groups all responsive rules for the same breakpoint together
How to Use
- Input CSS only - Paste pure CSS code (no
<style>tags, HTML, or JavaScript) - Click "Clean CSS" - The tool will analyze and optimize your stylesheet
- Review the output - Check the statistics and cleaned CSS in the right panel
- Optional settings - Toggle property sorting or minification as needed
- Copy the result - Use the "Copy to Clipboard" button to get your cleaned CSS
⚠️ Important: Always backup your original CSS before replacing it with the cleaned version. While we haven't encountered any issues in testing, it's best practice to keep a copy of your original code.
Features
- Duplicate Removal - Eliminates selectors that are defined multiple times
- Rule Consolidation - Combines selectors with identical properties into grouped rules
- Media Query Merging - Consolidates scattered
@mediaqueries for the same breakpoint - Property Sorting - Optional alphabetical sorting of CSS properties within rules
- CSS Minification - Optional removal of whitespace for production-ready output
- CSS Beautification - Works in reverse! Paste minified CSS to get readable, formatted output
- Bidirectional Parser - Accepts both minified and prettified CSS as input, outputs either format
Input CSS
Cleaned CSS
How It Works
The Cleaning Process
The CSS Cleaner uses a multi-step process to optimize your stylesheets:
- Parsing - The tool parses your CSS into structured data, separating regular rules,
@mediaqueries,@keyframes,@font-face, and other at-rules - Deduplication - When a selector appears multiple times, later definitions override earlier ones (following CSS cascade rules)
- Grouping - Selectors with identical properties are automatically grouped together using comma-separated lists
- Consolidation - Media queries with the same breakpoint are merged into single blocks
- Regeneration - Clean CSS is generated in the proper order: imports → font-faces → regular rules → media queries → keyframes
Real-World Example
If your CSS has grown organically with multiple developers adding rules over time, you might have:
.button { color: red; }
.nav { padding: 10px; }
.button { background: blue; }
@media (max-width: 768px) { .nav { padding: 5px; } }
.button { padding: 10px; }
@media (max-width: 768px) { .button { font-size: 14px; } }After cleaning, you'll get:
.button {
color: red;
background: blue;
padding: 10px;
}
.nav {
padding: 10px;
}
@media (max-width: 768px) {
.nav {
padding: 5px;
}
.button {
font-size: 14px;
}
}Tips for Best Results
- Test thoroughly - After cleaning, verify your site looks identical before committing changes
- Use version control - Commit your original CSS before replacing it with the cleaned version
- Keep it readable - For development, leave minification off. Only minify for production deployment
- Sort properties - Enable alphabetical sorting if your team prefers consistent property order
- Run periodically - Clean your CSS whenever you notice it's grown messy or after major feature additions
- Combine with build tools - This tool complements (doesn't replace) build tools like PostCSS or cssnano
What Gets Preserved
The tool maintains all critical CSS features and structure:
- CSS cascade and specificity rules
- Vendor prefixes (
-webkit-,-moz-, etc.) - Pseudo-elements and pseudo-classes
- Keyframe animations (including vendor-prefixed versions)
- Complex selectors and combinators
- Custom properties (CSS variables)
!importantdeclarations
Performance Impact
While CSS optimization provides modest performance gains compared to other optimizations (like image optimization or JavaScript reduction), every byte counts:
- Typical savings: 10-30% file size reduction for organically-grown stylesheets
- Load time impact: Minimal but measurable improvement, especially on slower connections
- Developer time saved: Significant - clean CSS is easier to debug and modify
- Maintenance benefits: Reduced confusion about which rules actually apply
Browser Compatibility
The tool runs entirely in your browser using vanilla JavaScript - no server-side processing required. It works in all modern browsers (Chrome, Firefox, Safari, Edge). The cleaned CSS output is standard CSS that works everywhere the original did.