GTmetrix analyzes a web page and reports on performance metrics including load time, page size, and Core Web Vitals. It gives a letter grade, a list of recommendations ordered by impact, and a waterfall chart showing how resources loaded. Tests can be run from multiple regions and on different connection speeds with a paid account.

The recommendations are practical: compress images, defer scripts, leverage caching, reduce redirects. For developers and site owners who want a straightforward performance audit without configuring a testing environment, GTmetrix provides a clear report. The free tier allows a limited number of tests per day. It pairs well with WebPageTest for deeper analysis.