Build a CAPTCHA System to Prevent Bot Attacks

Bots can overwhelm your platform with spam, brute-force login attempts, or fake registrations. CAPTCHA systems help distinguish humans from automated tools by introducing challenges that are easy for people but hard for machines — adding a crucial security layer to forms and APIs.

This project aims to build different CAPTCHA types such as image-based selection, character recognition, math puzzles, and behavioral CAPTCHAs. It integrates them into user-facing forms and validates submissions using server-side logic to prevent automation-based abuse.

The CAPTCHA is embedded into your form. On submission, the frontend sends the user's answer to the server for validation. If the response is correct (or behavior is human-like), the form is processed. Otherwise, the request is blocked or flagged as suspicious.

• CAPTCHA is generated and linked to a session/token on form load.
• User solves the CAPTCHA (text, math, image, or behavior-based).
• Answer is verified on the server before accepting the form submission.
• Rate-limiting or alerting mechanisms are triggered for repeated failures.
• Advanced CAPTCHAs track cursor movement or time taken to detect automation.

• Building a Custom CAPTCHA in Python
• Google reCAPTCHA Docs
• Accessible CAPTCHA Guidelines
• Pillow (Python Imaging Library)
• Bot Detection via Honeypot Fields