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Critical rendering path optimization

Critical CSS Generator

Extract the exact styles needed above the fold across multiple viewports, then ship a faster first render with less blocking CSS.

  • Multi-viewport analysis
  • Advanced selector control
  • CSS + HTML output
Generate critical CSS
Enter a page URL, then fine-tune viewports and extraction rules if needed.
Advanced configurationCustomize viewports and extraction rulesOptional

Viewport coverage

Select the screen sizes used for above-the-fold extraction.

Excluded rule types

Leave non-critical declarations out of the generated stylesheet.

Custom viewport

Add another screen size to the extraction pass.

Viewport dimensionsDimensions are measured in CSS pixels.

Always include selectors

Preserve important selectors even when they are outside the detected critical path.

Press Enter, comma, or space after each selector.

Prioritize the first render

Make the critical rendering path genuinely critical

Deliver only the styles needed for the initial view, then let the rest of the page catch up without blocking it.
01

Improve above-the-fold rendering

Critical CSS is the CSS required to render the content visible when a page first loads. By extracting and inlining only the styles needed for the initial viewport, you can reduce render-blocking CSS and help browsers display meaningful content sooner. This can improve perceived loading speed and create a faster experience for visitors.

The Critical CSS Generator automatically analyzes a page and generates the CSS required for above-the-fold content. It supports multiple viewport sizes, allowing you to generate critical CSS for mobile, tablet, desktop, or custom screen dimensions. Advanced options also provide control over ignored rules and force-included selectors, making the generated output more accurate for complex websites.

02

Reduce render-blocking CSS

Large stylesheets can delay rendering because browsers typically need to download and process CSS before displaying content. Critical CSS helps solve this by prioritizing the styles needed for the initial view while the remaining styles load afterward. This technique is widely used to improve loading performance and optimize the critical rendering path.

This tool is useful for developers, performance engineers, agencies, and website owners looking to improve page speed metrics and user experience. Whether you're optimizing a landing page, ecommerce store, blog, or SaaS application, generating critical CSS can help reduce render-blocking resources and deliver faster visual loading for your visitors.

Frequently Asked Questions

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