Unfortunately, the website "http://www.similarweb.com/" is inaccessible due to a server permission issue. As a result, users are unable to access any content or features on the site. The server returns a "Reference #18.ca82617.1691779571.3d12e16a" error message when attempting to access the site. This error message suggests that the server has restricted access or denied permission to the user. Consequently, it is not possible to provide a comprehensive summary of the website's utility as it cannot be accessed at this time.