Skip to content

x402 Payments

Gate any HTTP endpoint behind a stablecoin payment. Payers sign off-chain — no gas fees on EVM, no pre-approval required. Your server middleware handles verification and settlement in one call.

Works on Base, Solana, and Radius today. Use the hosted facilitator at x402.stablecoin.xyz — no infrastructure to run.

npm install @stablecoin.xyz/x402

How it works

Server — add one middleware call to gate your endpoint:

import { x402Middleware } from '@stablecoin.xyz/x402/middleware/express'
 
app.get('/premium', x402Middleware({
  payTo: '0xYourAddress',
  amount: '1000000000000000', // 0.001 SBC
  network: 'base',
  apiKey: process.env.API_KEY,
}), handler)

Client — client.fetch is a drop-in for fetch. It handles the 402, signs the payment, and retries automatically:

import { createX402Client, viemSignerAdapter } from '@stablecoin.xyz/x402/evm'
 
const client = createX402Client({ signer: viemSignerAdapter(walletClient), network: 'base' })
const res = await client.fetch('https://api.example.com/premium')

The payment flow:

Client                     Your Server              x402.stablecoin.xyz
  │                             │                           │
  ├──── GET /premium ──────────►│                           │
  │◄─── 402 + payment terms ────┤                           │
  │                             │                           │
  │  (signs off-chain, no gas)  │                           │
  │                             │                           │
  ├──── GET /premium ──────────►│                           │
  │     + PAYMENT-SIGNATURE     ├──── verify + settle ─────►│
  │                             │◄─── tx confirmed ─────────┤
  │◄─── 200 + your data ────────┤                           │

The facilitator executes the on-chain transfer. Your route handler only runs after payment is confirmed.

Networks

type NetworkKey =
  | 'base'           // Base mainnet     — 18 decimals
  | 'base-sepolia'   // Base Sepolia      — 6 decimals  (testnet, free)
  | 'radius'         // Radius mainnet    — 6 decimals
  | 'radius-testnet' // Radius testnet    — 6 decimals  (testnet, free)
  | 'solana'         // Solana mainnet    — 9 decimals
  | 'solana-devnet'  // Solana Devnet     — 9 decimals  (testnet, free)
NetworkKeyDecimalsStatus
Basebase18Mainnet
Base Sepoliabase-sepolia6Testnet (free)
Radiusradius6Mainnet
Radius Testnetradius-testnet6Testnet (free)
Solanasolana9Mainnet
Solana Devnetsolana-devnet9Testnet (free)

Testnet networks require no API key. Start on base-sepolia or radius-testnet or solana-devnet to test without real funds.

Hosted facilitator

SBC runs a hosted facilitator — no infrastructure to deploy or maintain.

Value
URLhttps://x402.stablecoin.xyz
EVM signer0xdeE710bB6a3b652C35B5cB74E7bdb03EE1F641E6
Solana signer2mSjKVjzRGXcipq3DdJCijbepugfNSJCN1yVN2tgdw5K

Mainnet networks (base, radius, solana) require an API key passed as the X-API-Key header. Get yours at dashboard.stablecoin.xyz.

Next