Free Critical CSS Checker — Find Render-Blocking CSS
Identify render-blocking CSS that is delaying your page's First Contentful Paint and Largest Contentful Paint scores.
Free — no account required for a single check. Sign up for continuous monitoring →
What the Critical CSS Checker checks
Render-blocking CSS files identified
Critical CSS coverage analysis
Above-the-fold CSS requirements
Unused CSS in critical path
Recommendations for inlining critical CSS
How it works
Analyses the CSS loading waterfall during page load to identify stylesheets in the critical rendering path that block FCP and LCP.
Monitor continuously — not just once
This free tool runs a one-off check. AuditJet monitors your site on a schedule — alerting you when scores change, before performance regressions affect your rankings and revenue.
Critical CSS Checker — FAQ
Is the Critical CSS Checker free?
Yes — Critical CSS Checker is completely free to use. No account required for a single-URL check.
How does the Critical CSS Checker work?
Analyses the CSS loading waterfall during page load to identify stylesheets in the critical rendering path that block FCP and LCP.
What does the Critical CSS Checker check?
Render-blocking CSS files identified. Critical CSS coverage analysis. Above-the-fold CSS requirements. Unused CSS in critical path. Recommendations for inlining critical CSS.
How is this different from Google PageSpeed Insights?
Google PageSpeed Insights is a one-off manual tool. AuditJet adds continuous monitoring, regression alerting, and revenue impact on top of the same performance analysis — so you're notified when scores change, not just when you remember to check.