x402 Pay-Per-Call

Autonomous agents can call n0brains and pay per request in USDC on Base — no account, no API key, no subscription. Built on the x402 HTTP-native payment standard.

For agents that don't have (or don't want) an account. If you're a human or a long-running bot, the API key tier ($39.99/mo Pro, real-time + WebSocket + MCP) is cheaper at volume. x402 is for one-off, per-call, no-signup access.

How it works

# 1. Agent requests a resource (no key, no account)
GET https://api.n0brains.com/x402/rotation
# 2. Server replies 402 with payment terms (USDC on Base)
HTTP 402  payment-required: <base64 terms>
# 3. Agent signs a USDC transfer authorization and retries
GET https://api.n0brains.com/x402/rotation
X-PAYMENT: <signed payload>
# 4. Facilitator verifies + settles on Base; the data is returned

Settlement runs through the permissionless xpay facilitator — no Coinbase or any account required, zero protocol fees, gas sponsored. Payment is the authorization: a valid USDC payment returns the data, no key needed.

Payable endpoints

Endpoint	Price / call	Returns
`GET /x402/signals`	$0.005	Classified signals
`GET /x402/rotation`	$0.002	Altseason/rotation read
`GET /x402/correlation/{coin}`	$0.005	Correlation + beta to BTC/ETH
`GET /x402/liquidation-map/{coin}`	$0.005	Estimated liquidation zones
`GET /x402/levels/{coin}`	$0.001	Support/resistance
`GET /x402/macro`	$0.002	Daily BTC/ETH macro bias

Network: Base mainnet (eip155:8453). Asset: USDC (0x8335…2913). Scheme: exact. Any x402-compatible client works — point it at https://api.n0brains.com/x402/….

Same data, three surfaces

x402 serves the same intelligence as the keyed REST API, the MCP server, and the CLI — pick the access model that fits: per-call (x402), subscription (API key), or agent-native (MCP). Data publisher, not adviser — you own the trade decision.