HTTP 402 "Payment Required" has existed since 1999. x402 finally made it real — sign a USDC transfer, attach it to your request, get the resource. No API keys. No billing. Just GET -> 402 -> sign -> 200.

x402plus takes it further. Same protocol. Same 402 flow. But now: multi-chain (EVM + Solana + Movement), gasless, with identity.

x402       GET /api -> 402 -> sign USDC transfer -> pay on-chain -> 200
x402plus   GET /api -> 402 -> sign intent        -> settle off-chain -> 200

x402plus introduces the intent scheme — a new payment method that complements x402's existing exact scheme. Both live inside the same 402 response. The client picks. The backend doesn't care.

x402 works. But it hits walls fast:

x402plus adds one concept: the GRID ID.

A GRID ID is a non-custodial smart account (Safe vault) powered by Stableyard. You deposit once. Then you sign intents — gasless, cross-chain, off-chain settled.

1. Deposit USDC to your GRID ID (any chain, one time)
2. Request a paid API
   GET /api/premium -> 402 Payment Required
3. Sign an intent (one signature, zero gas)
   Facilitator gets a quote -> you sign it -> done
4. Get the resource
   GET /api/premium + X-PAYMENT -> 200 OK

Your GRID ID balance decreases. Merchant gets paid.
No gas. No bridging. No chain switching.

Every x402plus 402 response offers multiple schemes and networks. Clients choose based on what they have:

{
  "x402Version": 1,
  "accepts": [
    { "scheme": "exact",  "network": "polygon",   "payTo": "0x...",  "asset": "0x3c49..." },
    { "scheme": "exact",  "network": "solana-devnet", "payTo": "So1...", "asset": "4zMM...", "extra": { "feePayer": "..." } },
    { "scheme": "exact",  "network": "movement",  "payTo": "0x00...", "asset": "0x4d29..." },
    { "scheme": "intent", "network": "polygon",   "payTo": "0x...",  "facilitatorUrl": "https://..." }
  ]
}

Backward compatible. Any x402 client that supports exact works out of the box. Solana, Movement, and intent schemes are additive.

import { x402plus } from "@stableyard/x402plus";

app.use(x402plus("0xYourAddress", {
  "GET /api/premium":    0.10,   // $0.10 per request
  "POST /api/generate":  5.00,   // $5.00 per generation
}));

// Your endpoint — unchanged. Only reached after payment.
app.get("/api/premium", (req, res) => {
  res.json({ data: "premium content" });
});

No facilitator URL. No USDC addresses. No chain config. Just a wallet address and dollar amounts.

Add Solana and/or Movement alongside EVM:

app.use(x402plus("0xYourEVMAddress", {
  "GET /api/premium": 0.10,
}, {
  defaultChain: "polygon",
  solana: { payTo: "YourSolanaAddress" },
  movement: { payTo: "0x00...YourMovementAddress" },
}));

One facilitator. One endpoint. Payments from MetaMask, Phantom, and Nightly all work.

Use any standard x402 facilitator for exact EVM payments:

app.use(x402plus("0xYourAddress", routes, "https://x402.org/facilitator"));

Or run your own — see GUIDE.md.

import { withPayments } from "@stableyard/x402plus/client";

const paidFetch = withPayments(window.ethereum);
const res = await paidFetch("https://api.example.com/premium");

See GUIDE.md for complete integration with EVM, Solana, Movement, and Intent examples.

git clone https://github.com/stableyardfi/x402plus
cd x402plus

# Terminal 1 — Facilitator
cd facilitator && npm install && npm run dev

# Terminal 2 — API server
cd backend && npm install && npm run dev

# Terminal 3 — Frontend
cd frontend && npm install && npm run dev

One-time setup. Then every payment is just sign and go.

 Create      ->  Activate   ->  Deposit    ->  Pay
 GRID ID         Vault          USDC           Intent
 POST            Sign Safe      Send USDC      Sign EIP-712
 /account        module tx      to deposit     per request
                                address

<--- one-time setup ---------------------->    <-- every payment

Native tokens (SOL, MOVE) supported via explicit opt-in: { solanaPrice: 0.001, movementPrice: 1.0 }.

                      x402plus (scheme)

  exact (EVM)     exact (Solana)     exact (Movement)
  EIP-3009        TransferChecked    USDC.e / MOVE
       |                |                 |
       +--------+-------+---------+-------+
                |
         intent (x402plus)
         EIP-712 Stableyard settlement
                |
   facilitator.stableyard.fi
   (single URL — all chains)

   Internally routes per chain:
     EVM      -> native or proxy
     Solana   -> native or proxy
     Movement -> native or proxy

     Stableyard
     GRID ID - Settlement - Yield - Identity

x402plus is the scheme — open, composable, anyone can implement it.

Stableyard is the infrastructure — GRID ID vaults, cross-chain settlement, yield, identity.

packages/x402plus/   SDK — middleware, types, facilitator client, multi-chain support
facilitator/         Reference facilitator (single URL, routes all chains)
backend/             Demo API server
frontend/            Demo UI with EVM + Solana + Movement wallets + GRID ID flow

PAY_TO=0xYourEVMAddress

# Optional
NETWORK=base                    # default chain (default: base)
SOLANA_PAY_TO=YourSolanaAddress  # enables Solana support
MOVEMENT_PAY_TO=0xYourMoveAddr   # enables Movement support

STABLEYARD_BASE_URL=https://api.stableyard.fi
STABLEYARD_APP_ID=your-app-id
STABLEYARD_APP_SECRET=your-app-secret
FACILITATOR_PRIVATE_KEY=0x...

# Optional chain proxies
SOLANA_PROXY_URL=https://x402.org/facilitator
EVM_PROXY_URL=https://x402.org/facilitator

• GUIDE.md — Integration guide for backend and frontend developers
• x402.org — The base x402 protocol
• Stableyard — GRID ID infrastructure
• Safe — Smart account standard

Apache-2.0

x402plus — extending x402 with cross-chain intents
Settlement infrastructure by Stableyard