YesWeHack is described as 'Bug Bounty Platform'. There are four alternatives to YesWeHack for Online / Web-based. The best alternative is HackerOne. It's not free, so if you're looking for a free alternative, you could try Open Bug Bounty or Bugcrowd.
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.