Easily check if a certain e-mail address is valid. Is it a valid domain? Is the e-mail a temporary/disposable e-mail? That’s a common indicator of spamming/trolling, so now there’s an API for you so you can easily block it!
Newly Registered Domains API (v1) lets you check which domains have been added.
WHOIS API (v1) returns well-parsed WHOIS records with fields in JSON formats for any domain name.