Installation

Python

Requirements

• Python 3.9 or higher
• pip package manager

Install

pip install x402-client httpx eth-account

# Verify installation
python -c "from x402.client import X402Client; print('OK installed')"

Virtual Environment (Recommended)

python -m venv foursec-env
source foursec-env/bin/activate  # Linux/Mac
# foursec-env\Scripts\activate   # Windows

pip install x402-client httpx eth-account

JavaScript / Node.js

Requirements

• Node.js 18 or higher
• npm or yarn

Install

# Using npm
npm install @x402/client ethers

# Using yarn
yarn add @x402/client ethers

cURL / CLI

npm install -g @x402/cli
x402 --version

Verify Everything Works

from x402.client import X402Client
from eth_account import Account
import httpx

wallet = Account.create()
client = X402Client(wallet=wallet)

# Test free endpoint (no payment needed)
response = httpx.get("https://api.foursec.xyz/health")
print(response.json())
# {"status": "healthy", "version": "2.1.0", ...}

TIP

The /health endpoint is free — no wallet or payment needed. Use it to verify connectivity.

Network Configuration

client = X402Client(
    wallet=wallet,
    facilitator_url="https://x402.org/facilitator",
    rpc_url="https://mainnet.base.org",
    chain_id=8453,  # Base mainnet
)

Troubleshooting

Issue	Solution
ModuleNotFoundError: x402	Run pip install x402-client
Connection refused	Check firewall, API is at port 443
Insufficient balance	Add USDC to wallet on Base network
Invalid chain	Ensure wallet is on Base (chain ID 8453)