Primer

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Primer on SKALE

• Primer Pay — Chrome extension that automatically handles x402 payments as you browse. Install from the Chrome Web Store.
• MultiClaw — Desktop app for authorizing AI agent payments. Delegate spending authority with daily caps, per-request limits, and domain restrictions — your keys never leave the device. Available as a portable executable or via pip install multiclaw.
• Test Paywall Generator — Instantly generate a working x402 paywall to test your integration.
• x402 Validator — Validate x402 payment headers and debug formatting issues.

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Prerequisites

• A wallet with USDC (or any ERC-20) on SKALE Base
• Basic understanding of x402 protocol — learn more here

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Supported Networks

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Integration with Primer SDK

npm install @primersystems/x402

const { x402Hono } = require("@primersystems/x402");
const { Hono } = require("hono");
const { serve } = require("@hono/node-server");

const app = new Hono();

app.use("*", x402Hono(process.env.RECEIVING_ADDRESS, {
  "/api/premium": {
    amount: "0.001",
    asset: "0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20", // USDC on SKALE Base
    network: "eip155:1187947933",                          // SKALE Base Mainnet
  },
}));

app.get("/api/premium", (c) => {
  return c.json({ message: "Payment verified on SKALE Base!" });
});

serve({ fetch: app.fetch, port: 3000 });

const { createSigner, x402Fetch } = require("@primersystems/x402");

const signer = await createSigner("eip155:1187947933", process.env.PRIVATE_KEY);
const fetch402 = x402Fetch(fetch, signer, { maxAmount: "1.00" });

const response = await fetch402("http://localhost:3000/api/premium");
console.log(await response.json());

pip install primer-x402[fastapi]  # or primer-x402[flask]

from fastapi import FastAPI
from primer_x402 import x402_fastapi

app = FastAPI()

app.add_middleware(x402_fastapi(
    '0xYourWalletAddress',
    {
        '/api/premium': {
            'amount': '0.001',
            'asset': '0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20',  # USDC on SKALE Base
            'network': 'eip155:1187947933',                           # SKALE Base Mainnet
        }
    }
))

@app.get('/api/premium')
async def premium():
    return {'message': 'Payment verified on SKALE Base!'}

from primer_x402 import create_signer, x402_requests

signer = create_signer('eip155:1187947933', os.environ['PRIVATE_KEY'])

with x402_requests(signer, max_amount='1.00') as session:
    response = session.get('http://localhost:3000/api/premium')
    print(response.json())

# TypeScript
npx @primersystems/x402 probe https://api.example.com/paid
X402_PRIVATE_KEY=0x... npx @primersystems/x402 pay https://api.example.com/paid --max-amount 0.10

# Python
x402 probe https://api.example.com/paid
X402_PRIVATE_KEY=0x... x402 pay https://api.example.com/paid --max-amount 0.10

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Prism: Full ERC-20 Support

1. Payer approves the Prism contract once (one-time on-chain transaction)
2. For each payment, the payer signs an EIP-712 authorization off-chain
3. The facilitator calls settleERC20() on Prism to execute the transfer
4. Prism moves tokens from payer to payee — gasless on SKALE

curl https://x402.primer.systems/contracts

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Primer Pay: Browser Extension

• Automatic interception — patches fetch and XMLHttpRequest to detect 402 responses
• Spend controls — per-payment limits, daily caps, confirmation thresholds
• Multi-network balances — view balances across all supported SKALE networks
• Transaction history — track all payments by domain and network

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MultiClaw: Agent Payment Authorization

• Key isolation — agents receive tokens with spending limits, not your private keys
• Spend policies — daily caps, per-request limits, auto-approve thresholds, domain restrictions
• Multi-agent support — register unlimited agents, each with their own policy.
• Universally compatible — fast setup with all types of agent, any model.
• Portable — download as a standalone executable (runs from USB) or pip install multiclaw

# Install via pip
pip install multiclaw[gui]

# Or download the portable executable from GitHub
# https://github.com/primer-systems/multiclaw/releases

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Developer Tools

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API Reference

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Next Steps

• SKALE Supported Facilitators — See all available facilitators
• Run Your Own Facilitator — Deploy your own facilitator infrastructure
• Accept Payments — Protect endpoints with payment middleware
• Make Payments — Build clients that handle x402 payments

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Resources

• Primer Documentation
• Primer Pay (Chrome Web Store)
• MultiClaw (GitHub)
• x402 SDK — TypeScript
• x402 SDK — Python
• x402 Protocol Specification