GTmetrix is a website speed and performance optimization tool, quite similar to Google PageSpeed Insights. It loads your site, assignes scores and provides actionable recommendations on how to optimize it, that are split by grade, type and priority (PageSpeed tab). The interface is very rich with hints, tips and useful additional info.

There are 5 tabs, the most precious are the first 3 of them: PageSpeed, YSlow and Waterfall. Yslow looks just like PageSpeed, but gives a list of things that slow your websites’ loading down. The Waterfall tab shows a timeline that reflects a websites’ loading behavior. Helpful for issues discovery. Click the red button on the right to download the .PDF report.

GTmetrix is actually a freemium tool with a PRO version, but I list it here as a free tool because the free version because this version is very powerful.