Critical CSS Extractor

Extract critical CSS from your HTML and CSS to improve page load times and performance. This tool helps you identify and separate the CSS needed for above-the-fold content.

HTML Input

CSS Input

What is Critical CSS?

Critical CSS is the minimal CSS required to render the above-the-fold content of a webpage. Extracting and inlining this CSS can significantly improve page load times by:

  • Reducing render-blocking resources
  • Displaying content to users faster
  • Improving Core Web Vitals metrics like First Contentful Paint (FCP)
  • Enhancing the perceived performance of your website

The non-critical CSS can be loaded asynchronously after the page has rendered, further optimizing the user experience.

About the Critical CSS Extractor

The Critical CSS Extractor helps you identify and separate the CSS needed for above-the-fold content on your web pages. By extracting and inlining this critical CSS, you can significantly improve page load times and Core Web Vitals scores.

What is Critical CSS?

Critical CSS is the minimum set of CSS rules needed to render the above-the-fold content of a webpage (the portion visible without scrolling). By inlining this CSS in the <head> of your HTML document, you can render the visible portion of your page quickly while the rest of your CSS loads asynchronously.

Why Critical CSS Matters

Faster Perceived Load Times

By inlining critical CSS, users see the above-the-fold content almost immediately, creating the perception that your site loads quickly even before all resources are fully loaded.

Improved Core Web Vitals

Critical CSS directly improves metrics like First Contentful Paint (FCP) and Largest Contentful Paint (LCP), which are key factors in Google's page experience ranking signals.

Eliminate Render-Blocking Resources

External CSS files are render-blocking by default, meaning the browser pauses rendering until they're downloaded. Critical CSS allows you to load your main CSS files asynchronously.

Better Mobile Performance

On slower mobile connections, critical CSS makes an even bigger difference, ensuring users don't abandon your site while waiting for it to render.

How the Critical CSS Extractor Works

  1. Paste your HTML code in the HTML input area
  2. Paste your full CSS in the CSS input area
  3. The tool analyzes which HTML elements are likely to appear above the fold
  4. It extracts only the CSS rules that apply to those elements
  5. The result is a minimal set of CSS rules needed for initial rendering

How to Implement Critical CSS

Basic Implementation

<!DOCTYPE html>
<html>
<head>
  <!-- Inline critical CSS -->
  <style>
    /* Paste your critical CSS here */
  </style>

  <!-- Load full CSS asynchronously -->
  <link rel="preload" href="styles.css" as="style" onload="this.onload=null;this.rel='stylesheet'">
  <noscript><link rel="stylesheet" href="styles.css"></noscript>
</head>
<body>
  <!-- Your content -->
</body>
</html>

Pro Tip

Critical CSS should be regenerated whenever you make significant changes to your site's layout or styling. Consider automating this process in your build pipeline using tools like Critical, CriticalCSS, or Penthouse.