Robot verification popups prevent automated attacks while maintaining user experience. Implement CAPTCHA alternatives that balance security with accessibility. Consider invisible reCAPTCHA that runs in the background, only showing challenges when suspicious activity is detected.

hCaptcha provides privacy-focused verification with options for accessibility. Puzzle-based verification offers game-like interactions that are user-friendly. Always provide audio alternatives for visually impaired users. Implement progressive challenges - start with simple checks before escalating to more complex verification.

Place verification appropriately in user flows, typically during sign-up, login, or sensitive actions. Monitor verification success rates and adjust difficulty if needed. Avoid blocking legitimate users with overly aggressive verification. Test across different devices and browsers to ensure compatibility.