Minify your HTML by removing all the unnecessary characters.
Minify your JS by removing all the unnecessary characters.
Get approximate IP details.
Get all possible details about an SSL certificate.
Ping a website, server or port..
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Check if the URL is banned and marked as safe/unsafe by Google.
Get all the HTTP headers that an URL returns for a typical GET request.