tiagozip

cap

Security#CAPTCHA#JavaScript#Proof-of-Work#Docker#Web Security

// summary

Cap is a lightweight, open-source alternative to traditional visual CAPTCHAs that utilizes SHA-256 proof-of-work and JavaScript instrumentation. It eliminates the need for user-solved puzzles while ensuring privacy by avoiding telemetry and external tracking. The solution is highly customizable, dependency-free, and can be deployed via Docker or any JavaScript runtime.

// technical analysis

Cap is a lightweight, privacy-focused CAPTCHA alternative that replaces traditional visual puzzles with SHA-256 proof-of-work challenges and JavaScript instrumentation. By eliminating the need for user-facing image recognition tasks, it improves accessibility and user experience while maintaining robust bot protection. The project prioritizes performance and simplicity, offering a dependency-free architecture that can be deployed across various JavaScript runtimes or via Docker for standalone operation.

// key highlights

Utilizes proof-of-work challenges to replace frustrating visual puzzles, allowing users to bypass manual verification.

Achieves a small footprint of approximately 20kb with zero dependencies, making it significantly faster than traditional alternatives like hCaptcha.

Ensures user privacy by design, as the system does not transmit telemetry data back to external servers.

Offers full visual customization through CSS variables, allowing developers to seamlessly integrate the widget into any UI design.

Supports a standalone Docker mode that includes built-in analytics for easier monitoring and management.

Provides programmatic access to solve challenges in the background, enabling protection for APIs and machine-to-machine communication.

// use cases

Replacing visual CAPTCHAs with automated proof-of-work challenges

Protecting APIs from malicious bots while allowing access for friendly robots

Implementing privacy-first, zero-dependency bot protection in web applications

// getting started

To begin using Cap, visit the official documentation at capjs.js.org to explore integration guides and feature comparisons. Developers can choose to implement it directly within any JavaScript runtime or deploy the standalone version using the provided Docker container. You can also test the functionality immediately by trying the live demo available on the project's documentation site.