Product Introduction

1. Cap is a lightweight open-source CAPTCHA alternative that replaces traditional challenge-response systems with SHA-256-based proof-of-work (PoW) to distinguish humans from bots. It operates without tracking, cookies, or data collection, prioritizing privacy and efficiency.
2. The core value of Cap lies in its ability to provide robust bot mitigation while maintaining user privacy, reducing computational overhead, and offering full customization for seamless integration into diverse applications.

Main Features

1. Cap’s widget library is 250x smaller than hCaptcha, weighing only 12kb when minified and compressed with Brotli, ensuring minimal impact on page load times.
2. It uses SHA-256 proof-of-work to validate users, eliminating the need for invasive tracking or fingerprinting while maintaining compatibility with all modern browsers.
3. The solution is fully self-hostable, allowing developers to customize both frontend and backend components using CSS variables or direct code modifications.

Problems Solved

1. Cap addresses the privacy concerns and performance bottlenecks associated with traditional CAPTCHAs like reCAPTCHA, which rely on tracking and large libraries.
2. It targets developers and organizations needing a lightweight, privacy-compliant bot mitigation tool for APIs, forms, or authentication systems.
3. Typical use cases include preventing API abuse, blocking spam submissions on contact forms, and securing free-tier services from automated exploitation.

Unique Advantages

1. Unlike reCAPTCHA or Cloudflare Turnstile, Cap replaces behavioral analysis with computation-based PoW, making it inherently privacy-preserving and resistant to fingerprinting.
2. Its standalone Docker mode enables integration with non-JavaScript ecosystems via a REST API, bypassing dependency on Node.js, Deno, or Bun runtimes.
3. Cap’s combination of open-source licensing (Apache 2.0), zero dependencies, and sub-50ms validation latency provides a competitive edge in scalability and transparency.

Frequently Asked Questions (FAQ)

1. How does Cap verify users without tracking? Cap uses SHA-256 proof-of-work challenges that require clients to solve computational puzzles, which are trivial for humans but costly for bots, without collecting personal data.
2. Can Cap be self-hosted? Yes, Cap supports full self-hosting with Docker, allowing customization of both challenge generation and validation logic to meet specific security or branding requirements.
3. Is Cap compatible with non-JavaScript backends? Cap’s standalone Docker mode provides a REST API for generating and validating challenges, making it compatible with any programming language or framework.