Critical CSS Extractor & Compressor
Extract the minimal CSS needed to render above-the-fold content and compress it for inline embedding. The critical css extractor parses your HTML elements, matches them against your full CSS stylesheet, and outputs minified critical CSS ready to inline in your <head> — eliminating render-blocking CSS and improving Largest Contentful Paint (LCP) scores. All processing happens in your browser with no signup required.
Critical CSS Extractor & Compressor
Paste your HTML and CSS, click "Extract Critical CSS", and get the minimal CSS needed to render above-the-fold content — minified and ready to inline in your <head>. All processing happens locally in your browser. Your code never leaves your device.
HTML Markup
Paste your above-the-fold HTML
Full CSS Stylesheet
Paste your full CSS file
What is critical CSS?
Critical CSS is the minimal set of CSS rules needed to render above-the-fold content without waiting for the full stylesheet to load. Inlining it in your <head> eliminates render-blocking CSS and improves Largest Contentful Paint (LCP) scores.
Why Use Our Critical CSS Extractor?
Instant Critical CSS Extraction in Your Browser
Extract critical CSS instantly in your browser — no server upload, no Puppeteer, no headless browser. The critical css extractor parses your HTML elements and matches them against your CSS rules in milliseconds, entirely on your device.
Secure Critical CSS Extractor Online
Your HTML and CSS never leave your device. The critical css extractor runs entirely in your browser — no server uploads, no data transmission, 100% private. Safe for proprietary stylesheets, internal tools, and production codebases.
Three Output Formats for Every Workflow
The critical css extractor outputs minified CSS, a ready-to-paste <style> snippet, or readable formatted CSS — switch between formats with one click. Shows exact rule count and byte savings so you can measure LCP impact.
100% Free Forever
The critical css extractor is completely free with no signup, no premium tier, no file size limits, and no ads. Extract critical CSS from unlimited pages at zero cost, forever.
Common Use Cases for Critical CSS Extractor
Core Web Vitals LCP Optimization
Eliminate render-blocking CSS to improve Largest Contentful Paint (LCP) scores — a key Core Web Vitals metric. The critical css extractor identifies the minimal CSS needed to render above-the-fold content, which you inline in your <head> while loading the full stylesheet asynchronously.
Next.js and React Performance Optimization
Extract critical CSS for Next.js, React, and Vue pages to reduce Time to First Byte (TTFB) and First Contentful Paint (FCP). The critical css extractor works with any framework — paste the rendered HTML and your CSS bundle to get the inline-ready critical styles.
Shopify and E-Commerce Speed Optimization
Improve Shopify store page speed scores by inlining critical CSS for product pages, collection pages, and the homepage. The critical css extractor helps identify which Shopify theme CSS rules are needed above the fold to eliminate render-blocking stylesheet requests.
WordPress Page Speed Improvement
Extract critical CSS for WordPress themes to reduce render-blocking resources flagged by Google PageSpeed Insights. The critical css extractor works with any WordPress theme — paste the page HTML and your theme's CSS to get the critical inline styles.
Landing Page Performance Optimization
Maximize landing page load speed by inlining only the CSS needed for above-the-fold content. The critical css extractor is ideal for marketing landing pages where every millisecond of LCP improvement directly impacts conversion rates.
Static Site Generator Optimization
Automate critical CSS extraction for Astro, Hugo, Eleventy, and Jekyll sites — paste the generated HTML and your CSS to get the critical inline styles. The critical css extractor helps you implement the critical CSS pattern without a build-time Puppeteer dependency.
Understanding Critical CSS Extraction
What is Critical CSS?
Critical CSS is the minimal set of CSS rules required to render the above-the-fold content of a web page — the portion visible without scrolling. When a browser encounters a <link rel="stylesheet"> tag, it blocks rendering until the entire stylesheet is downloaded and parsed. By inlining critical CSS directly in the <head> and loading the full stylesheet asynchronously, you eliminate render-blocking CSS — one of the most impactful optimizations for Largest Contentful Paint (LCP) and First Contentful Paint (FCP) scores. Our critical css extractor identifies which CSS rules match your HTML elements and outputs a minified, inline-ready stylesheet.
How Our Critical CSS Extractor Works
- 1Paste Your HTML and CSS:Enter your above-the-fold HTML markup and your full CSS stylesheet into the two input panels. Use "Load sample" to try the extractor with a realistic example. Upload .html and .css files directly using the upload buttons.
- 2Click "Extract Critical CSS": The extractor parses your HTML to identify all elements (tags, classes, IDs, attributes), then matches each CSS rule against those elements. Rules that match are included in the critical CSS output. Base rules (html, body, *, :root), @keyframes, and @font-face are always included. Processing runs entirely in your browser.
- 3Choose Output Format and Copy:Switch between minified CSS, a ready-to-paste <style> snippet, or readable formatted CSS. Copy to clipboard or download. Inline the <style> snippet in your <head> and load the full stylesheet asynchronously.
What Gets Included in Critical CSS
- Matched Selectors: CSS rules whose selectors match elements present in your HTML — by tag name, class, ID, or attribute. Comma-separated selectors are checked individually.
- Base Styles: Rules targeting html, body, *, :root, ::before, and ::after are always included — these affect the entire page layout and must be available immediately.
- @keyframes and @font-face: Animation keyframes and font-face declarations are always included — they are referenced by other critical rules and must be available before rendering.
- @media Query Rules: Media query blocks are included if their inner selectors match your HTML elements — ensuring responsive above-the-fold styles are available on all screen sizes.
Important Limitations
The critical css extractor uses static HTML analysis — it matches CSS selectors against the HTML elements you provide. It does not execute JavaScript, so dynamically added classes and elements are not detected. For the most accurate results, paste the server-rendered HTML of your page (the initial HTML before JavaScript runs). Complex CSS selectors involving descendant combinators (e.g. .parent .child) are matched against the last token only — this may include some non-critical rules. Always review the output before inlining in production.
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Frequently Asked Questions About Critical CSS Extractor
A critical css extractor identifies the minimal set of CSS rules needed to render above-the-fold content and outputs them as a minified, inline-ready stylesheet. Our free critical css extractor online parses your HTML elements and matches them against your CSS rules entirely in your browser. Your code never leaves your device.
Copy the <style> snippet output and paste it inside your <head> tag. Then load your full stylesheet asynchronously to avoid render-blocking: <link rel="preload" href="styles.css" as="style" onload="this.rel='stylesheet'"><noscript><link rel="stylesheet" href="styles.css"></noscript>. This pattern eliminates render-blocking CSS while ensuring the full stylesheet loads for below-the-fold content.
Yes, completely. The critical css extractor runs entirely in your browser using native JavaScript. Your HTML and CSS are never uploaded to any server and never leave your device. All parsing and matching happens locally — safe for proprietary stylesheets, internal tools, and production codebases.
Yes — 100% free, forever. No signup, no account, no premium tier, no file size limits, and no ads. Extract critical CSS from unlimited pages completely free.
The critical css extractor uses static HTML analysis and matches CSS selectors against the elements in your HTML. Complex descendant selectors (e.g. .parent .child) are matched against the last token only, which may include some rules for elements not visible above the fold. Always review the output and remove any rules that are clearly not needed for above-the-fold rendering.
No — the critical css extractor uses static HTML analysis and does not execute JavaScript. For the most accurate results, paste the server-rendered HTML of your page (the initial HTML before JavaScript runs). For React, Next.js, and Vue apps, use the SSR/SSG output or the page source viewed with JavaScript disabled.
The critical css extractor supports tag selectors (div, h1), class selectors (.hero), ID selectors (#header), attribute selectors ([data-id]), comma-separated selectors, and pseudo-class/pseudo-element selectors (which are stripped for matching). Complex combinators (descendant, child, sibling) are supported by matching against the last token in the selector chain.
Typical pages achieve 60–90% CSS size reduction for the critical path — a 100 KB stylesheet often has only 5–15 KB of critical CSS. The critical css extractor shows exact rule counts and byte savings so you can measure the impact before implementing.
There is no artificial file size limit. The practical limit depends on your browser's available memory. For typical stylesheets — even large ones with thousands of rules — the critical css extractor processes them instantly.