There are several major providers of application security solutions, including:

1. Checkmarx: A comprehensive application security solution that provides both static and dynamic application security testing (SAST and DAST).
2. Veracode: A cloud-based application security platform that offers SAST, DAST, and interactive application security testing (IAST) solutions.
3. Rapid7: An application security provider that offers web application scanning and penetration testing services.
4. OWASP: A non-profit organization that provides free, open-source tools for application security testing and management.
5. Contrast Security: An application security solution that uses runtime application self-protection (RASP) technology to continuously monitor and protect applications.
   

The choice of the best provider depends on the specific needs of an organization and its resources. It’s recommended to carefully evaluate each provider and its offerings to determine the best fit for your organization.