One of the best tools for checking website speed and performance testing is Google PageSpeed Insights
The tool presents the page speed of your website on both mobile and desktop. The maximum pass test score you can get is 100. The higher the score, the better the performance of the website.
Page Speed Insights not only provides the performance optimization test result of your website but also provides you the necessary suggestions to improve your website speed and performance.
Google's Page Speed is very popular for testing the speed of both the mobile and desktop versions of a website. Produces a detailed report on key web metrics and what actions need to be taken to improve your website's performance for your audience.