Your First Request

Walk through a complete request lifecycle step by step.

Step 1: Check API Health (Free)

import httpx

response = httpx.get("https://api.foursec.xyz/health")
print(response.json())

Response:

{
  "status": "healthy",
  "version": "2.1.0",
  "uptime_seconds": 86400,
  "total_requests": 150000,
  "supported_symbols": ["ETH", "BTC", "SOL", "ARB", "OP", "MATIC", "AVAX", "DOT", "LINK", "UNI"]
}

Step 2: Get Available Endpoints (Free)

response = httpx.get("https://api.foursec.xyz/")
print(response.json())

Response:

{
  "name": "4SEC Market Data API",
  "version": "2.1.0",
  "endpoints": [
    {"path": "/price/:symbol", "method": "GET", "price": "$0.01"},
    {"path": "/price/history/:symbol", "method": "GET", "price": "$0.02"},
    {"path": "/volume/:symbol", "method": "GET", "price": "$0.01"},
    {"path": "/arbitrage-opportunity", "method": "GET", "price": "$0.03"},
    {"path": "/volatility-index/:symbol", "method": "GET", "price": "$0.02"}
  ]
}

Step 3: Make a Paid Request

from x402.client import X402Client
from eth_account import Account

wallet = Account.from_key("0x_your_key")
client = X402Client(wallet=wallet)

response = client.get("https://api.foursec.xyz/price/ETH")
print(f"Status: {response.status_code}")
print(response.json())

The Payment Flow

Behind the scenes:

1. client.get("/price/ETH") — sends GET request
2. API responds: 402 Payment Required with payment details
3. x402 client decodes: amount=0.01 USDC, network=Base
4. Client signs USDC transfer (EIP-712 typed data)
5. Client retries request with payment proof in headers
6. API verifies payment on-chain
7. API returns 200 + data

Cost Summary

Request	Cost	Cumulative
GET /health	$0.00	$0.00
GET /	$0.00	$0.00
GET /price/ETH	$0.01	$0.01
GET /price/ETH (within 30s)	$0.00	$0.01
Total		$0.01

Next Steps

• API Reference — All endpoints
• Python SDK — Advanced patterns
• Payment Flow — Deep dive