Castle secures your authentication stack in minutes with threat monitoring and account hijack protection, completely invisible to your users. Know in real-time who's logged in, where they're coming from, and what they're doing. Whenever something suspicious happens you're alerted via email, Slack or webhooks and can immediately lock the affected user accounts. Castle protects from brute force attacks, detects TOR and proxy logins, and lets you see users that are logging in from the same devices and IPs.