GTMetrix
GTmetrix was developed as a tool for customers to easily test the performance of their webpages. Whether you're on desktop or mobile, low or high-end hardware, or half-way around the world - your experience with the web should be fast.
Pagespeed.web.dev
PageSpeed Insights (PSI) reports on the user experience of a page on both mobile and desktop devices, and provides suggestions on how that page may be improved. PSI provides both lab and field data about a page.
Pingdom Speed Test
We built this Website Speed Test to help you analyze your website load speed. The test is designed to help make your site faster by identifying what about a webpage is fast, slow, too big, and so on.
Uptrends
With Google’s Core Web Vitals and W3C navigation timing metrics, you can view exactly when your webpage has performed important load events such as, First Contentful Paint (FCP) or Time to first byte (TTFB), for example.
Debugbear
DebugBear helps online businesses speed up their websites and meet Google's Core Web Vitals criteria. This web based in the UK and have been making website faster since 2018.