Convert text to binary and the other way for any string input.
Convert text to hexadecimal and the other way for any string input.
Convert text to ascii and the other way for any string input.
Convert text to octal and the other way for any string input.
Extract email addresses from any kind of text content.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get approximate IP details.
Take an IP and try to look for the domain/host associated with it.
Get & verify the meta tags of any website.
Get all the HTTP headers that an URL returns for a typical GET request.