sequenceDiagram
    participant App as Your App
    participant Agnic as AgnicPay
    participant API as Paid API
 
    App->>Agnic: POST /api/x402/fetch?url=...
    Agnic->>API: Forward request
    API-->>Agnic: 402 Payment Required
    Agnic->>Agnic: Sign payment
    Agnic->>API: Retry with payment header
    API-->>Agnic: 200 OK + Response
    Agnic-->>App: Response + payment info

POST /api/x402/fetch?url={target_url}

curl -X POST "https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/data" \
  -H "X-Agnic-Token: agnic_tok_YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -H "X-Custom-Header: value"

curl -X POST "https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/generate&method=POST" \
  -H "X-Agnic-Token: agnic_tok_YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "Write a poem about AI",
    "max_tokens": 500
  }'

curl -X POST "https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/data" \
  -H "X-Agnic-Token: agnic_tok_YOUR_TOKEN"

curl -X POST "https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/generate&method=POST" \
  -H "X-Agnic-Token: agnic_tok_YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"prompt": "Hello world"}'

# Max payment of $0.50 (500000 atomic units)
curl -X POST "https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/data&maxValue=500000" \
  -H "X-Agnic-Token: agnic_tok_YOUR_TOKEN"

import requests
 
response = requests.post(
    "https://api.agnic.ai/api/x402/fetch",
    params={
        "url": "https://api.example.com/paid-endpoint",
        "method": "POST"
    },
    headers={
        "X-Agnic-Token": "agnic_tok_YOUR_TOKEN",
        "Content-Type": "application/json"
    },
    json={
        "prompt": "Generate something"
    }
)
 
# Check if payment was made
if response.headers.get("X-Agnic-Paid") == "true":
    print(f"Paid ${response.headers.get('X-Agnic-Amount')}")
 
print(response.json())

const response = await fetch(
  'https://api.agnic.ai/api/x402/fetch?url=https://api.example.com/data&method=POST',
  {
    method: 'POST',
    headers: {
      'X-Agnic-Token': 'agnic_tok_YOUR_TOKEN',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ prompt: 'Hello' })
  }
);
 
// Check payment info
const paid = response.headers.get('X-Agnic-Paid');
const amount = response.headers.get('X-Agnic-Amount');
 
if (paid === 'true') {
  console.log(`Paid $${amount}`);
}
 
const data = await response.json();

{
  "error": "insufficient_balance",
  "error_description": "Not enough USDC balance to complete payment"
}

{
  "error": "spending_limit_exceeded",
  "error_description": "Payment of $0.50 exceeds per-transaction limit of $0.25"
}

{
  "error": "payment_exceeds_max",
  "error_description": "Required payment exceeds maxValue parameter"
}