Name:WhoIsXML API (Free)
URL:https://www.whoisxmlapi.com/
Utility:This free tool – 

• Provides cyber threat intelligence data 
• Finds domain data including domain age, registrant details etc
• Monitor and protect “terms” that come under the Intellectual Property
• Monitor web asset acquisitions and fraudulent online transactions, identify investment opportunities and verify merger and spinoff activities
• Safeguard against payment transaction fraud 

Special Features:

• Real-time APIs
• Database downloads