Castle is a platform to stop bots and account abuse in minutes by connecting to Cloudflare or using own edge stack. It provides SDK to monitor users and stop fraud in-app, offering enterprise security without friction. Castle offers dual-layer fraud defense running at the edge and in-app as one system, with signals flowing between both layers. Features include behavioral analysis, device fingerprinting (99.5% accurate), bot detection, AI scoring for account takeover attempts and abusive behavior, rules engine for real-time actions, email intelligence, case & state management, proactive threat hunting with user behavior analytics, pattern exploration, network analysis, session monitoring, rule backtesting, and custom security flows.