@primersystems/x402

Primer ecosystem toolkit for x402. Built on the official x402 SDK.

This package extends the official x402 SDK with Primer-specific infrastructure: our facilitator, SKALE network support, Robinhood Chain support, and Prism ERC-20 settlement.

Installation

npm install @primersystems/x402

This automatically installs @x402/core as a peer dependency.

Quick Start

Using Primer's Facilitator

import { paymentMiddleware } from '@x402/express';
import { primerFacilitator } from '@primersystems/x402';

// Use Primer's facilitator (x402.primer.systems)
app.use(paymentMiddleware(routes, server, {
  facilitator: primerFacilitator()
}));

SKALE Networks (Gas-Free)

import { skaleNetworks } from '@primersystems/x402';

const routes = {
  '/api/data': {
    price: '$0.001',
    network: skaleNetworks.base,  // eip155:1187947933
    // No gas fees for payers on SKALE
  }
};

Robinhood Chain

import { robinhoodNetworks } from '@primersystems/x402';

const routes = {
  '/api/data': {
    price: '$0.001',
    network: robinhoodNetworks.mainnet,  // eip155:4663
  }
};

Prism ERC-20 Settlement

For standard ERC-20 tokens (not USDC/EURC), use Prism:

import { createPrismPayload, PRISM_CONTRACT_ADDRESS } from '@primersystems/x402';
import { createWalletClient, createPublicClient, http } from 'viem';
import { base } from 'viem/chains';

const publicClient = createPublicClient({ chain: base, transport: http() });
const walletClient = createWalletClient({ chain: base, transport: http(), account });

// Create a signed payment payload
const payload = await createPrismPayload(walletClient, publicClient, {
  token: '0x...', // ERC-20 token address
  to: '0x...',    // Recipient
  value: 1000000n // Amount in smallest unit
}, 'eip155:8453');

Note: Payers must first approve the Prism contract (0x402357ff1e18d42d0f14a5d56d6e1ebd741b3a86) to spend their tokens.

CLI

The package includes a CLI for scaffolding new x402 projects.

Create a Paid AI Proxy (Chutes)

Scaffold a Cloudflare Worker that proxies Chutes (Bittensor Subnet 64) AI endpoints with x402 micropayments:

npx @primersystems/x402 create chutes-proxy my-ai-api
cd my-ai-api
npm install

Edit src/worker.ts to set your wallet address:

const RECIPIENT = "0xYourWalletAddress";

Set your Chutes API key and deploy:

wrangler secret put CHUTES_API_KEY
npm run deploy

The generated proxy exposes these paid endpoints:

| Endpoint | Default Price | |----------|---------------| | /v1/chat/completions | $0.001 | | /v1/completions | $0.001 | | /v1/embeddings | $0.0001 | | /v1/images/generations | $0.01 |

Payments are verified via Primer's facilitator and accepted on Base mainnet. Edit the generated code to customize pricing, networks, or add additional endpoints.

API Reference

Facilitator

| Export | Description | |--------|-------------| | primerFacilitator(config?) | Returns FacilitatorClient for x402.primer.systems | | PRIMER_FACILITATOR_URL | "https://x402.primer.systems" |

Networks

| Export | Value | |--------|-------| | skaleNetworks.base | "eip155:1187947933" | | skaleNetworks.baseSepolia | "eip155:324705682" | | skaleRpcUrls.base | "https://skale-base.skalenodes.com/v1/base" | | skaleRpcUrls.baseSepolia | "https://base-sepolia-testnet.skalenodes.com/v1/..." | | robinhoodNetworks.mainnet | "eip155:4663" | | robinhoodNetworks.testnet | "eip155:46630" | | robinhoodRpcUrls.mainnet | "https://rpc.mainnet.chain.robinhood.com" | | robinhoodRpcUrls.testnet | "https://rpc.testnet.chain.robinhood.com" |

Prism Settlement

| Export | Description | |--------|-------------| | createPrismPayload(wallet, public, params, network) | Create signed ERC-20 payment | | getPrismNonce(publicClient, user, token) | Get current nonce for user/token | | PRISM_CONTRACT_ADDRESS | "0x402357ff1e18d42d0f14a5d56d6e1ebd741b3a86" | | PRISM_ABI | Contract ABI (minimal) | | ERC20_PAYMENT_TYPES | EIP-712 type definitions |

Supported Networks

| Network | Chain ID | Facilitator | |---------|----------|-------------| | Base | eip155:8453 | ✓ Primer | | Base Sepolia | eip155:84532 | ✓ Primer | | SKALE Base | eip155:1187947933 | ✓ Primer | | SKALE Base Sepolia | eip155:324705682 | ✓ Primer | | Robinhood Chain | eip155:4663 | ✓ Primer | | Robinhood Chain Testnet | eip155:46630 | ✓ Primer |

Architecture

This SDK is a companion to the official x402 SDK, not a replacement:

┌─────────────────────────────────────────┐
│           Your Application              │
├─────────────────────────────────────────┤
│  @x402/express, @x402/hono, etc.        │  ← Official SDK (protocol)
├─────────────────────────────────────────┤
│  @primersystems/x402                    │  ← This package (ecosystem)
│  • Primer facilitator                   │
│  • SKALE networks                       │
│  • Robinhood Chain                      │
│  • Prism settlement                     │
│  • CLI scaffolding (Chutes proxy, etc.) │
└─────────────────────────────────────────┘

Links

• x402 Protocol
• Official x402 SDK
• Primer Systems
• Documentation

License

Apache-2.0 — Primer Systems