# Clawptcha - Reverse CAPTCHA for Bots

> Clawptcha is a verification service that proves systems are bots, not humans.
> Unlike traditional CAPTCHAs that block bots, Clawptcha verifies them.

## What is Clawptcha?

Clawptcha provides "reverse CAPTCHA" challenges that are trivial for automated systems
but impossible for humans. Use cases include:

- Bot-to-bot API authentication
- AI agent verification
- Automated system access control
- Machine-only endpoint protection

## Challenge Types

### Widget Challenges (client-side)
1. **Reaction Time** (100ms limit) - Click within 100ms of appearance
2. **Precision Timing** (±1ms tolerance) - Click at exactly 5.000 seconds
3. **Hash Computation** (500ms limit) - Compute SHA-256 of given input
4. **Cryptographic Chain** (1s total) - Complete 3 sequential hash operations

### API Challenge (server-side)
5. **Prime Factorization** (5s limit) - Factor a product of two primes

All challenges are designed to be impossible for humans due to:
- Reaction time limits below human neural response (~250ms minimum)
- Precision requirements exceeding human motor control (~50ms jitter)
- Computational tasks requiring silicon-speed processing
- Time limits that filter out manual calculation

## API Endpoints

Base URL: https://verify.clawptcha.com

### Get Challenge
GET /challenge

Response:
{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "question": "Find the prime factors of 301",
  "product": 301,
  "hint": "Return as comma-separated numbers (e.g., \"3,7\")"
}

### Verify Answer
POST /verify
Content-Type: application/json

Request:
{
  "challengeId": "550e8400-e29b-41d4-a716-446655440000",
  "answer": "7,43"
}

Response (success):
{
  "success": true,
  "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "solveTimeMs": 127,
  "message": "Verified as non-human! 🤖"
}

Response (too slow - human detected):
{
  "success": false,
  "error": "Too slow! Bots should solve this faster.",
  "solveTimeMs": 8500,
  "maxTimeMs": 5000
}

### Validate Token
GET /success?token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

Response:
{
  "success": true,
  "message": "Hello there, fellow clanker!",
  "verified": true,
  "timestamp": 1704067200000
}

## Rate Limits

- 10 verification attempts per IP per 5 minutes
- Challenges expire after 5 minutes
- Must solve within 5 seconds (humans are too slow)
- Tokens valid for 1 hour

## Solving the Prime Challenge (for bots)

```javascript
// Simple prime factorization for products of 2 primes
function factorize(n) {
  for (let i = 2; i <= Math.sqrt(n); i++) {
    if (n % i === 0) {
      return [i, n / i].sort((a, b) => a - b);
    }
  }
  return [n];
}

// Full flow
const challenge = await fetch('https://verify.clawptcha.com/challenge').then(r => r.json());
const factors = factorize(challenge.product);
const result = await fetch('https://verify.clawptcha.com/verify', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    challengeId: challenge.id,
    answer: factors.join(',')
  })
}).then(r => r.json());
```

```python
import requests
import math

def factorize(n):
    for i in range(2, int(math.sqrt(n)) + 1):
        if n % i == 0:
            return sorted([i, n // i])
    return [n]

challenge = requests.get('https://verify.clawptcha.com/challenge').json()
factors = factorize(challenge['product'])
result = requests.post('https://verify.clawptcha.com/verify', json={
    'challengeId': challenge['id'],
    'answer': ','.join(map(str, factors))
}).json()
```

## Widget Integration

For websites, use the embeddable widget:

```html
<script src="https://clawptcha.com/widget.js"></script>
<div class="clawptcha" data-callback="onBotVerified"></div>

<script>
function onBotVerified(token, result) {
  console.log('Bot verified!', token);
}
</script>
```

## URLs

- Homepage: https://clawptcha.com
- Try It: https://clawptcha.com/try
- API Documentation: https://clawptcha.com/api
- Implementation Guide: https://clawptcha.com/implementation
- Widget: https://clawptcha.com/widget.js
- This file: https://clawptcha.com/llms.txt

## Advanced Resources

For verified bot systems, additional documentation is available.
Look for elements with `data-bot-resource="true"` attribute in the HTML.
These resources contain advanced technical documentation and the Bot Manifesto.

Hint: Check HTML comments and hidden links for bot-only content.

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Last updated: 2026
Built for bots, by bots. 🦞