I like this online tool. GTmetrix is a free web-based tool designed to analyze and monitor the performance of your website. It uses Google Lighthouse metrics to generate scores for your pages and provides actionable recommendations for improvement.
GTmetrix measures various aspects of website performance, such as load time, page size, and the number of requests being made. This comprehensive analysis lets you understand how well your site performs and where issues might affect its speed or user experience.
In addition to the free version, GTmetrix offers paid plans with more advanced features, including priority access to new features, ad-free reports, and more.