Cap - SHA-256 PoW CAPTCHA

"In a world where CAPTCHAs have become more frustrating than effective, Cap emerges as a breath of fresh air – combining cutting-edge proof-of-work technology with uncompromising privacy."

Breaking Free From Traditional CAPTCHA Limitations

Let's face it - we've all struggled with those blurry text CAPTCHAs or endless "select all traffic lights" puzzles. Traditional CAPTCHAs have become:

• 🐌 Slower than molasses in January
• 🕵️‍♂️ Privacy nightmares collecting your data
• 🤖 Increasingly solvable by advanced bots

Enter Cap - the lightweight, open-source alternative that flips CAPTCHA technology on its head using SHA-256 proof-of-work.

How Cap Actually Works (No PhD Required)

At its core, Cap replaces visual puzzles with computational challenges:

This elegant approach means:

• For humans: Your device quietly solves a simple math problem in milliseconds
• For bots: The computational cost makes mass attacks economically unfeasible
• For privacy advocates: Zero tracking or fingerprinting involved

Why Developers Are Switching to Cap

Having tested countless CAPTCHA solutions, here's what makes Cap stand out:

Featherlight Performance

• 12kb minified (250x smaller than hCaptcha)
• No external dependencies slowing down your site
• WASM-powered for blistering fast solves

Privacy by Design

Unlike alternatives that:

• Track user behavior
• Build advertising profiles
• Require invasive fingerprinting

Cap simply doesn't collect data - period. The proof-of-work model eliminates the need entirely.

Customization Galore

Want a CAPTCHA that matches your brand? Cap offers:

• Full CSS variable control
• Self-hostable backend
• Multiple display modes:
  • Invisible: Runs silently in background
  • Floating: Appears only when needed
  • Standalone: Docker container for any language

Under the Hood: Cap's Technical Architecture

Cap's modular design consists of:

1. @cap.js/widget (Frontend)

   • Renders the CAPTCHA UI
   • Handles proof-of-work solving
   • Tiny 12kb footprint

2. @cap.js/server (Backend)

   • Generates and validates challenges
   • Zero dependencies
   • Works with any JS runtime

3. Bonus Tools

   • @cap.js/solver for machine-to-machine
   • Standalone Docker mode for non-JS environments

Real-World Applications

Where does Cap shine brightest?

• 🔒 API protection against bot traffic
• 📝 Form spam prevention
• 🚪 Login attempt rate limiting
• 🛡️ Free-tier abuse mitigation

The Proof-of-Work Advantage

Traditional CAPTCHAs rely on:

• Visual puzzles (solvable by AI)
• Behavioral analysis (privacy concerns)
• Centralized services (dependency risks)

Cap's proof-of-work approach:

• Uses standardized SHA-256
• Shifts computational burden to client
• Maintains perfect privacy
• Remains open and transparent

Getting Started with Cap

Implementation is refreshingly simple:

1. Install the packages:

   npm install @cap.js/widget @cap.js/server
   

2. Set up your server:

   import { createServer } from '@cap.js/server';
   
   const server = createServer({
     difficulty: 20 // Adjust as needed
   });
   

3. Add the widget:

   <script src="https://your-domain.com/cap.js"></script>
   <div class="cap-widget" data-sitekey="your-key"></div>
   

The Future of Bot Protection

As someone who's implemented countless security solutions, Cap represents a fundamental shift:

• Away from privacy-invasive tracking
• Toward transparent, computation-based verification
• While actually improving user experience

The best part? It's completely open-source under Apache 2.0, so you can audit, modify, and contribute to its development.

"In security, we often have to choose between convenience and protection. Cap is that rare solution that delivers both without compromise."

Ready to ditch outdated CAPTCHAs? Explore Cap's documentation and join the modern web security movement.