Unused CSS Finder

Paste HTML and CSS to find and remove unused CSS rules. Shows byte savings.

HTML

CSS

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What is this

What is the Unused CSS Finder?

Paste your CSS and HTML to identify CSS rules with no matching elements. Remove dead code and reduce stylesheet size.

Everything runs locally in your browser. Adjust the controls above, preview instantly, and copy clean, production-ready CSS — no account, no upload.

How to use

Using the Unused CSS Finder

Everything lives in the panel at the top of this page. There is nothing to install — it all runs right here in your browser.

Paste your HTML

Paste the HTML of the page you want to audit.

Paste your CSS

Paste the CSS stylesheet to check against the HTML.

Identify unused rules

Unused rules are highlighted in red. Review before deleting — dynamically added classes (via JavaScript) will appear unused but may be active at runtime.

The output

What the generated code looks like

Clean, production-ready CSS — no vendor bloat, no unnecessary declarations.

audit-result.css

/* UNUSED — no matching elements found in HTML */
.hero-badge { ... }
.sidebar-widget { ... }
.legacy-button { ... }
#popup-overlay { ... }

/* USED — at least one matching element */
.card { ... }
.btn-primary { ... }
h1, h2, h3 { ... }

The finder cross-references CSS selectors against the HTML. Class selectors are checked against class attributes. ID selectors against id attributes. Type selectors against tag names.

Common mistakes & fixes

Common mistakes & how to fix them

A few habits trip people up. Here is what to watch for — and the exact fix.

Deleting CSS rules added dynamically by JavaScript

JavaScript-added classes (modal--open, is-active, has-error) do not appear in the static HTML. The finder marks them as unused.

Fix: Review all flagged selectors before deletion. Check JavaScript files for className, classList.add, and setAttribute calls that reference the selector.

Pro tips

Pro tips for better results

★

For production auditing, use Chrome DevTools Coverage

Chrome DevTools > Sources > Coverage records exactly which CSS rules are applied during user interaction. It catches dynamically activated rules that static analysis misses.

FAQ

Frequently asked questions

Component-based CSS (React, Vue, Angular) often generates classes at build time. Static analysis against HTML will mark all component-generated classes as unused. This tool is best for traditional multi-page sites with static HTML.