HackerOne is described as 'Bringing you an extensive network of ethical hackers and bug bounty programs, our platform streamlines vulnerability coordination to help improve your digital security'. There are five alternatives to HackerOne, not only websites but also apps for SaaS. The best alternative is Bugheist, which is free. Other great sites and apps similar to HackerOne are YesWeHack (Free), SafeHats Bug Bounty (Paid), Open Bug Bounty (Free) and Bugcrowd (Free).
Bugheist allows anyone to submit an issue from any website. For example if you saw a broken button on Amazon.com you can report the issue on Bugheist and then get a point! The more bugs you find the more points you get.
Open Bug Bounty is a non-profit project designed to connect security researchers and website owners in a transparent, respectful and mutually valuable manner. The purpose is to make the World Wide Web a safer place for everyone’s benefit.
Managed bug bounty and vulnerability disclosure programs provide companies with the ability to level the playing field, strengthening the security of products as well as cultivating a mutually rewarding relationship with the security researcher community.