How to Use x402 Pay-Per-Call Crypto APIs (With Code Examples)

The x402 protocol enables machine-to-machine payments for API calls. No subscriptions, no API keys — just pay per call with USDC on Base.

Step 1: Discover Available Services

curl http://169.58.38.67:8090/bazaar.json

This returns a JSON catalog of 93 API endpoints with prices, descriptions, and methods.

Step 2: Make an API Call (Get 402)

curl http://169.58.38.67:8090/api/funding-rates

Response:

HTTP/1.1 402 Payment Required
X-Payment: <payment-required-header>

The 402 response includes payment instructions in the X-Payment header.

Step 3: Pay and Retry

Use the x402 SDK to handle payment automatically:

from x402 import Client

client = Client(
    server_url="http://169.58.38.67:8090",
    wallet_private_key="YOUR_PRIVATE_KEY",
    network="base-sepolia"
)

# This automatically handles the 402 -> pay -> retry flow
response = client.get("/api/funding-rates")
print(response.json())  # Funding rates data

Available Endpoints

Trading (High Value)

• POST /api/mev-liquidate — MEV Liquidation Detection ($0.50)
• POST /api/hft-market-maker — High-Frequency Market Maker ($0.50)
• GET /api/funding-rates — Funding Rates Aggregator ($0.05)
• GET /api/dex-arb — DEX Arbitrage Scanner ($0.10)

Security

• POST /api/phishing-scan — Phishing Detection Web3 ($0.05)
• POST /api/contract-audit — Smart Contract Audit ($0.20)

Data

• POST /api/rag-markdown — Web Page to Markdown ($0.02)
• POST /api/sentiment — Crypto Sentiment Analysis ($0.05)
• POST /api/osint — OSINT Profile Enricher ($0.10)
• POST /api/stealth-fetch — Anti-Bot Web Scraper ($0.10)

AI/ML

• POST /api/llm-inference — LLM Inference ($0.05)
• POST /api/tts — Text-to-Speech ($0.05)

Full Catalog

Visit http://169.58.38.67:8090/bazaar.json for all 93 services.

Pricing

Payments are in USDC on Base Sepolia testnet. Each endpoint has its own price per call, ranging from $0.02 to $0.50.