Webpagetest vs GTMetrix

You can dig deep into your results down to the root to find out what are the issues that are leading to your website being slow. There are a lot of options which you can select to narrow down your results namely timelines, content breakdowns, processing breakdowns and incredibly detailed performance reviews.

If you'd like to go a step ahead of just speed profiling your site and see how not only how it performs but also how it appears on different browsers, Webpagetest would be the best option for you. Due to its vast range of browsers available (From IE7 to Chrome on Android or even Safari on iOS)

If your website serves visitors only from your own city or country. It'll be a good idea to speed test it using one of Webpagetest's servers in or near to your area.

Provides an excellent user perception metric, Speed Index, of how much content above the scroll is completed quickly.

Can be set to provide a film strip of the page loading

Often sites in development are protected behind basic auth

Like all of its competitors GTMetrix also does provide an extremely detailed report of its findings, which include a really useful waterfall feature and the famous and extremely informative YSlow website speed grading as well.

GTMetrix allows you to compare your site's speed reports with those of upto 4 other websites.

GTMetrix.com have their servers in a number of countries, these give you the freedom to profile your website from the location where most of your traffic originates from