W3Test is a free, comprehensive website performance testing tool powered by Google Lighthouse. It analyzes your website's speed, SEO, accessibility, best practices, and Core Web Vitals to help you identify issues and improve your site.
Yes, W3Test is completely free to use. There are no hidden fees and no registration required. You can run unlimited tests and generate unlimited reports at no cost.
Core Web Vitals are a set of specific factors that Google considers important to a webpage's overall user experience. They include Largest Contentful Paint (LCP), which measures loading, Interaction to Next Paint (INP), which measures interactivity, and Cumulative Layout Shift (CLS), which measures visual stability. These metrics directly impact search rankings.
Performance scores range from 0 to 100. A score of 90 or above is considered good, 50 to 89 indicates the page needs improvement, and below 50 is considered poor. Scores are based on lab data collected by Lighthouse.
Most tests complete in 15-30 seconds. The time depends on the size and complexity of the website being tested.
W3Test can only test publicly accessible URLs. For local development testing, we recommend running Lighthouse directly in Chrome DevTools or using the Lighthouse CLI on your development machine.
W3Test uses Google Lighthouse, which is the industry standard for web performance testing. Results may vary slightly based on server response times, network conditions, and geographic location. We recommend running multiple tests at different times and averaging the results.
Yes, you can download any test report as a PDF file. Simply click the "Download PDF" button on any report page. PDF reports are perfect for sharing with your team or clients.
Website monitoring runs automated performance tests on a schedule you set (hourly, daily, weekly or monthly). It tracks your scores over time and shows you trends, so you can catch performance regressions early.
Review the recommendations in your report. Common fixes include optimizing images, minifying CSS and JavaScript, eliminating render-blocking resources, reducing JavaScript payloads, using a CDN, and improving server response times.
Yes, W3Test offers an API for developers who want to integrate performance testing into their own tools and workflows. See our documentation page for details.
W3Test stores the URLs and results of tests so that you can revisit reports and view trends. Read our Privacy Policy for full details on how data is handled.
Our servers launch Google Lighthouse headless Chrome against your public URL, collect the audit results, compute scores, and generate a detailed report with recommendations.
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