The best alternatives to Crowdcurity are Probely, Bugcrowd, and HackenProof. If these 3 options don't work for you, we've listed a few more alternatives below.
Probely finds vulnerabilities or security issues in web applications and provides guidance on how to fix them. Probe.ly was built having developers in mind and follows an API-First development approach, providing all features through an API. Get Secure!
Bug Bounty and Vulnerability Coordination Platform. By working with the community of white hat hackers we help companies uncover security vulnerabilities.
Pentest as a Service (PtaaS) platform that simplifies security and compliance needs of DevOps-driven teams with workflow integrations and high-quality talent on-demand.
Pearler is a set of tools that help vendors avoid the pain of RFx and security questionnaires. Pearler helps your teams work together, save time and send back answers that will seal the deal.