Minify your CSS by removing all the unnecessary characters.
Minify your JS by removing all the unnecessary characters.
Check if the URL is cached or not by Google.
Get approximate IP details.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Separate text back and forth by new lines, commas, dots...etc.
Get all possible details about a domain name.
Get all the HTTP headers that an URL returns for a typical GET request.