Castle, founded with the mission to enhance online security, focuses on preventing automated and human-originated account takeovers, fake accounts, and other behaviors that violate platform policies. Their core products include real-time velocity-based rules, resilient device fingerprinting, and deep user behavior analytics. Castle serves markets that require stringent security measures, such as e-commerce, fintech, and social media platforms, offering solutions to combat fake accounts, account takeovers, multi-accounting, content abuse, SMS pumping, and transaction abuse.

Notable affiliated individuals and investors have not been specified. Key achievements include developing a robust suite of security tools that provide deep visibility into user behavior and flexible self-managed lists. Castle's impact is significant in enhancing the security infrastructure of various online platforms, thereby protecting user data and maintaining the integrity of digital interactions.