GTmetrix

GTmetrix is a web-based tool for analyzing the performance of websites and web pages. It provides insights into load times, resource usage, and opportunities for improvement, helping developers optimize site speed and user experience. The service uses automated testing engines and combines data from established performance tools to generate its analysis. Historically it drew on Google PageSpeed Insights and YSlow, and in its current iterations incorporates elements from Lighthouse-based assessments as well.

Key outputs include page load time, total page size, and the number of requests, along with one or more performance scores. GTmetrix presents a waterfall chart showing how resources load over time and often includes a video capture of the loading process. The diagnostics section groups issues by category and offers actionable recommendations, such as minimizing render-blocking resources, optimizing images, enabling caching, and reducing unnecessary redirects.

Features and accessibility vary by plan. The free tier provides basic testing and limited history, while paid plans expand test locations and browser options, increase daily tests, improve historical reporting, enable scheduling and alerts, and may add advanced reporting and API access. Reports are accessible through the web interface, can be shared via links, and are often exportable to formats such as PDF, with additional data export options in higher-tier plans.

Typical use cases include benchmarking page performance, monitoring performance over time, and validating optimization efforts. GTmetrix is commonly used alongside other tools like PageSpeed Insights, Lighthouse, and related performance resources to identify and prioritize optimization work.