Maltego is proprietary software widely used for OSINT. Kali Linux includes the Community Edition of Maltego, which can be used for free with some limitations after completing the online registration. Maltego performs transforms over pieces of data (for example, email addresses, and domain names) to obtain more information, and it displays all of the results as a graph showing relationships among different objects. A transform is a search of public information about a particular object, for example, searches for IP addresses related to a domain name or social media accounts related to an email address or person's name. The following screenshot shows the main interface of Maltego:
Maltego interface