theHarvester is described as 'Collects emails, names, subdomains, IPs, and URLs from multiple public sources for open source intelligence in early penetration testing stages' and is an app in the network & admin category. There are more than 10 alternatives to theHarvester for a variety of platforms, including Linux, Windows, Mac, Self-Hosted and Web-based apps. The best theHarvester alternative is SpiderFoot, which is both free and Open Source. Other great apps like theHarvester are Blackbird OSINT, OSINT-tool, Prying Deep and sn0int.