The best alternatives to YesWeHack are Federacy, HackerOne, and Bugcrowd. If these 3 options don't work for you, we've listed a few more alternatives below.
Federacy is the first bug bounty platform built for startups. Our security researchers pentest your site and let you know if you have any exploitable vulnerabilities. It's free, you only pay for results.
BountyPage is an all-in-one platform that makes it easy to start and manage crowd-sourced vulnerability disclosure programs. It is an easy-to-use and accessible solution that enables you to launch a bug bounty program quickly and scale up over time.