Kerberos

Cloudflare Turnstile is a smart CAPTCHA alternative designed to provide a more user-friendly and privacy-focused approach to bot detection. It uses non-interactive challenges and machine learning to validate users without requiring them to solve puzzles or identify objects.

Imunify360 is a comprehensive security platform designed for Linux web servers. It utilizes machine learning technology and other advanced techniques to provide robust protection against various cyber threats, including malware, viruses, and other types of attacks, ensuring the integrity and performance of web hosting environments.

Akamai Web Application Protector is a cloud-based security solution designed for companies seeking an automated approach to web application firewall (WAF) and distributed denial-of-service (DDoS) protection. It provides real-time threat intelligence and adaptive security measures to defend against evolving web application attacks.

Friendly Captcha is an innovative proof-of-work based CAPTCHA alternative where the user's device performs computational work to prove humanity. This approach provides effective bot protection while offering a seamless, accessible user experience without traditional CAPTCHA challenges.

Slider Captcha is a free service that helps protect websites from spam and abuse.