Responsive site designs are key to attracting and keeping the attention of mobile phone users. Smartphones account for at least 80 percent of all the internet activity and organic searches performed online, and that percentage may increase in the upcoming years as the last few holdouts with flip phones finally convert to smartphones. One of the 10 best companies that offers responsive site design services is Constructive. The team at Constructive provides all of its clients with responsive site designs that can include additional features such as a platform for eCommerce. Constructive offers ongoing maintenance of the site. This is important because changes in mobile platforms or mobile device operating systems could impact the web browsers and the way that a site loads. Constructive also builds SEO into its responsive designs. As smartphone users increasingly use voice searches in order to get results, SEO and responsive design will work together.