x402 Payments

Four endpoints accept x402 payments as an alternative to an API key. Pay per request in USDC; no account required. For the concepts and a setup walkthrough, see the x402 guide.

Paid endpoints

Every other endpoint requires an x-api-key. A request that carries neither a valid key nor a payment on a paid route gets a 402; on a key-only route it gets a 401.

Discovery

To learn what a paid endpoint costs, request it without payment. The API returns 402 Payment Required with the accepted requirements:

curl -i "https://api.scanna.xyz/hot?limit=5"

{
  "x402Version": 1,
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "asset": "USDC",
      "maxAmountRequired": "10000",
      "payTo": "0x…",
      "resource": "https://api.scanna.xyz/hot",
      "description": "Trending markets feed"
    }
  ]
}

Each entry in accepts is one way to pay (one per configured network — Base and, when available, Solana). maxAmountRequired is in the asset's base units (USDC has 6 decimals, so 10000 = $0.01).

Paying

Sign a USDC payment for the quoted amount with your wallet and resend the request with the signed payload in the X-PAYMENT header. In practice an x402 client (x402-fetch, x402-axios) does this for you — see the guide examples.

On success the response is 200 with your data plus an X-PAYMENT-RESPONSE header carrying the on-chain settlement receipt (transaction hash + network).

How it differs from key auth

• No plan gating. A paid request bypasses Pro+ plan checks — paying for /predict unlocks it without a subscription.
• Not metered. x402 traffic isn't counted against any plan's usage; payment velocity is the only limiter.
• Mutually exclusive. A request is authorized by an API key or x402, not both. If a valid x-api-key is present, the request never reaches the payment flow.