Authentication

Learn how to authenticate your API requests. CaptchaKings API uses API keys for authentication.

Getting Your API Key

To use the API, you need an API key:

Register an account at captchakings.com/register
Login to your Dashboard
Navigate to API Settings
Copy your API key (format: ck_......)

⚠️ Keep Your API Key Secret!
Never expose your API key in frontend code, public repositories, or client-side applications.

Authentication Methods

We support 3 ways to authenticate your requests:

Method 1: Authorization Header (Recommended) ⭐

Pass your API key in the Authorization header as a Bearer token:

bash

curl -X POST https://captchakings.com/api/process.php \
  -H "Authorization: Bearer ck_your_api_key_here" \
  -F "captcha=@captcha.jpg"

php

$headers = [
    'Authorization: Bearer ' . $apiKey
];

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

Method 2: X-API-Key Header

Alternatively, use the X-API-Key header:

bash

curl -X POST https://captchakings.com/api/process.php \
  -H "X-API-Key: ck_your_api_key_here" \
  -F "captcha=@captcha.jpg"

Method 3: POST Parameter (Fallback)

You can also send the API key as a POST parameter:

bash

curl -X POST https://captchakings.com/api/process.php \
  -F "api_key=ck_your_api_key_here" \
  -F "captcha=@captcha.jpg"

💡 Best Practice: Use Method 1 (Authorization header) for better security and standard compliance.

Free Trial Mode

You can test the API without an API key using Free Trial Mode:

bash

curl -X POST https://captchakings.com/api/process.php \
  -F "captcha=@captcha.jpg"

⚠️ Free Trial Mode Limitations:
- No credits deducted (unlimited)
- Lower priority processing
- No usage tracking
- Best for testing only

Testing Your API Key

Verify your API key is working with this test request:

bash

# Replace with your actual API key
API_KEY="ck_your_api_key_here"

# Test request
curl -X POST https://captchakings.com/api/process.php \
  -H "Authorization: Bearer $API_KEY" \
  -F "captcha=@test_captcha.jpg"

Expected Response:

json

{
  "success": true,
  "data": {
    "prediction": "ABC123",
    "confidence": "98.5%"
  },
  "credits": {
    "credits_deducted": 1,
    "credits_remaining": 999,
    "plan": "free_trial"
  },
  "mode": "api_key"
}

Common Authentication Errors

Error	Cause	Solution
`Invalid API key or account inactive`	API key is wrong or account is disabled	Check your API key in the dashboard
`Insufficient credits`	You've run out of credits	Top up credits or upgrade your plan
`API authentication failed`	API key format is incorrect	Ensure API key starts with `ck_`

Security Best Practices

🔒 Security Tips:

Never commit API keys to Git - Use environment variables instead
Rotate keys regularly - Generate new keys every 3-6 months
Use HTTPS only - Never send requests over HTTP
Keep keys server-side - Don't expose keys in frontend JavaScript
Monitor usage - Check dashboard for suspicious activity

Example: Using Environment Variables

php

// .env file
CAPTCHAKINGS_API_KEY=ck_your_api_key_here

// In your PHP code
$apiKey = getenv('CAPTCHAKINGS_API_KEY');

// Or use $_ENV
$apiKey = $_ENV['CAPTCHAKINGS_API_KEY'];

python

# .env file
CAPTCHAKINGS_API_KEY=ck_your_api_key_here

# In your Python code
import os
api_key = os.getenv('CAPTCHAKINGS_API_KEY')

javascript

// .env file
CAPTCHAKINGS_API_KEY=ck_your_api_key_here

// In your Node.js code
require('dotenv').config();
const apiKey = process.env.CAPTCHAKINGS_API_KEY;

Next Steps

Now that you know how to authenticate, check out:

API Endpoints - Learn about available endpoints
Code Examples - See real implementation examples
Rate Limits - Understand usage limits