Social-Engineer Toolkit is described as 'The Social-Engineer Toolkit is an open source penetration testing framework designed for social engineering. SET has a number of custom attack vectors that allow you to make a believable attack quickly' and is a penetration testing tool in the network & admin category. There are more than 10 alternatives to Social-Engineer Toolkit for a variety of platforms, including Linux, Windows, Mac, Web-based and Self-Hosted apps. The best Social-Engineer Toolkit alternative is Metasploit. It's not free, so if you're looking for a free alternative, you could try Metasploit or PhoneSploit Pro. Other great apps like Social-Engineer Toolkit are mimikatz, ZoomEye, Exploit Pack and Sn1per Professional.