The first tool that you should definitely check out is YSlow from Yahoo. YSlow is a plug-in for Firebug, which is a must-have for all web developers. You can find the Firebug plug-in here: http://getfirebug.com/ and the YSlow plug-in here: http://developer.yahoo.com/yslow/. Firebug is activated by clicking the small bug icon in the bottom right part of the Firefox window. When visible you will get a new tab in Firebug as illustrated below:
You start the analyzer by browsing to the site you want to analyze and enable the “Autorun YSlow each time a web page is loaded” or by presseng the “Run test” button. In the following example, I’ve analyzed the URL “http://www.myrating.dk/indhold/3422-boller_i_karry” from one of my websites:
(By the way, “Boller i karry” is a great Danish dish. If you want to make it, a translated recipe is available here: http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=da&tl=en&u=http%3A%2F%2Fwww.myrating.dk%2Findhold%2F3422-boller_i_karry&act=url.)
You can click each rule, which shows a detailed description in the area at the right. YSlow typically shows a detailed description, explaining what you’ve done wrong as well as some hints on how to fix it. Note the “Read More” link at the bottom of each description, which will direct you toward a more detailed description at the developer.yahoo.com website.
I will go into each YSlow rule in detail in upcoming posts, but right now you know enough to start analyzing your own sites.