4SEC Market Data APIMulti-DEX Aggregated Crypto Prices

Quick Example ​

Get started in under 5 minutes. Install the x402 SDK and start fetching aggregated market data.

// Install: npm install @x402/fetch viem
import { wrapFetchWithPayments } from "@x402/fetch";
import { privateKeyToAccount } from "viem/accounts";
import { createWalletClient, http } from "viem";
import { base } from "viem/chains";

// 1. Setup wallet on Base network
const account = privateKeyToAccount("0x_your_private_key");
const walletClient = createWalletClient({
  account,
  chain: base,
  transport: http("https://mainnet.base.org"),
});

// 2. Create payment-enabled fetch
const fetchWithPayment = wrapFetchWithPayments(fetch, {
  client: walletClient,
});

// 3. Fetch real-time ETH price ($0.01 USDC)
const response = await fetchWithPayment(
  "https://api.foursec.xyz/price/ETH"
);
const data = await response.json();
console.log(`ETH: $${data.price_usd}`); // ETH: $2450.32

# Step 1: Make request (returns 402 Payment Required)
curl -i https://api.foursec.xyz/price/ETH

# Step 2: Use x402 CLI for automatic payment
npx x402-cli fetch \
  https://api.foursec.xyz/price/ETH \
  --key 0x_your_private_key

# Step 3: Get response with aggregated data
# {"symbol":"ETH","price_usd":2450.32,"sources":3,...}

# Install: pip install httpx web3 eth-account
import httpx

# Make request (see Python SDK for auto-payment)
response = httpx.get("https://api.foursec.xyz/price/ETH")

# Handle 402 payment flow
if response.status_code == 402:
    payment_header = response.headers.get("x-payment")
    # Sign USDC transfer and retry
    # See: /integration/python for full guide
    pass

# For simpler flow, use JavaScript SDK

Example Response ​

{
  "symbol": "ETH",
  "price_usd": 2450.32,
  "change_24h": 2.45,
  "volume_24h_usd": 12500000,
  "total_sources": 3,
  "spread": 0.07,
  "sources": [
    {
      "dex": "Uniswap V3",
      "price": 2450.30,
      "liquidity_usd": 5200000
    },
    {
      "dex": "BaseSwap",
      "price": 2450.35,
      "liquidity_usd": 3100000
    },
    {
      "dex": "SushiSwap",
      "price": 2450.28,
      "liquidity_usd": 4200000
    }
  ]
}

API Endpoints and Pricing ​

Pay-as-you-go with USDC on Base via the x402 protocol. No subscriptions, no commitments.

DEX Endpoints ​

Funding Rate Endpoints ​

Liquidation Endpoints ​

CEX Market Data (v1) ​

Free Endpoints ​

Supported DEXes ​

We aggregate prices from 8+ major decentralized exchanges across multiple chains:

Why Multi-DEX Aggregation? ​

Single-DEX prices can be misleading. Here's why aggregation matters:

• 🎯 Accurate Pricing — Volume-weighted average across multiple sources eliminates outliers
• 📉 Reduced Slippage — See real market depth, not just one pool's liquidity
• 💹 Arbitrage Detection — Spot price discrepancies across DEXes in real-time
• 🛡️ Manipulation Resistance — Harder to manipulate aggregated prices vs single source
• 📊 Better Risk Metrics — Spread analysis across all markets gives true volatility picture

How x402 Payment Works ​

The x402 protocol enables seamless pay-per-request API access:

Client                    4SEC API                  Base Network
  |                          |                          |
  |-- GET /price/ETH ------->|                          |
  |                          |                          |
  |<-- 402 Payment Required -|                          |
  |    (X-PAYMENT header)    |                          |
  |                          |                          |
  |-- Sign USDC transfer ----------------------------->|
  |                          |                          |
  |-- GET + Payment Proof -->|                          |
  |                          |-- Verify on-chain ------>|
  |                          |<-- Confirmed ------------|
  |                          |                          |
  |<-- 200 OK + Data --------|                          |
  |    {"price_usd": 2450.32}|                          |
  |                          |                          |

1. Request — Your app calls any API endpoint
2. 402 Response — API returns payment requirements in X-PAYMENT header
3. Sign — SDK automatically signs USDC transfer from your wallet
4. Retry — Client retries request with payment proof
5. Verify — API verifies payment on Base chain
6. Data — API returns the requested data

Who Uses 4SEC? ​

• 🤖 Trading Bots — Real-time price feeds for automated strategies
• 📊 Portfolio Trackers — Accurate valuations across all holdings
• 📱 Dashboards — Market data for analytics and monitoring
• 🔔 Alert Systems — Webhook notifications for price movements
• 💰 Funding Rate Arbitrage — Monitor extreme rates for short/long opportunities
• 🔥 Liquidation Monitors — Track cascades and risk levels
• 🏢 CEX Analysts — Compare DEX vs CEX prices for insights
• 🧠 AI Agents — Autonomous agents that pay for their own data
• 🔬 Research Tools — Historical data and risk analysis

Get Started ​

Ready to integrate? Choose your path:

Need Help? ​

• 📖 FAQ — Common questions and answers
• 🐛 Troubleshooting — Fix common issues
• 💬 GitHub — Report bugs and request features