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 decimal and the other way for any string input.
Convert text to octal and the other way for any string input.
Validate JSON content and make it looks good.
Get approximate IP details.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get all possible details about an SSL certificate.
Ping a website, server or port..
Take an IP and try to look for the domain/host associated with it.