Boss - Github, now with bounties
HackerOne - HackerOne provides a platform designed to streamline vulnerability coordination and bug bounty program by enlisting hackers.
Bugcrowd - Harness the largest pool of curated and ranked security researchers to run the most efficient bug bounty and penetration tests
Intruder - Intruder is a security monitoring platform for internet-facing systems.
Bounties Network - Complete tasks, earn crypto
Forcepoint Web Security Suite - Internet Security