Gtmetrix:Free online website Gtmetrix is a website optimization tool for website opening speed testing. After the test is completed, a PDF report can be generated and downloaded.

The loading speed of a website plays a very important role in the visitor's browsing experience is playing a very important role. As the webmaster must ensure that visitors can focus and spend more time on the content of the site, rather than waiting for the site to display, load images and scripts. Studies have shown that visitors generally do not tolerate more than four seconds of loading time on a site, and they will simply leave the site if they wait too long.

And GTmetrix is a free online analysis tool that can analyze the specific URLs you enter and display the scores on the results page after the test. You can also save this "report card" in pdf format for future use when improving and optimizing your website.

GTmetrix has two test metrics, one from google's page speed, and one from yahoo's Yslow. both are very authoritative analysis tools, so the results can very truly reflect the loading situation of the website.

In addition to the score, four tabs are displayed below, which show the test details of page speed, test details of Yslow, and the time spent on each element of the page after loading. The last history may save the data of your multiple tests of a web site, so that you can make comparisons from the displayed line graph.

The results shown in the first two tabs are very useful for website optimization, because it can tell you exactly what parts of the current page load need to be optimized. Red means that a test result score is very low, while green means that the score is very high and does not need to be optimized.

Improve the speed of web loading, in addition to bringing a good user experience, for optimization also has a small help, because any search engine, whether it is google or baidu, will be the web loading speed score as an indicator of the ranking algorithm.