Crypto Order Book ($0.004/call)

Live order book for a crypto pair (e.g. BTC-USD). Default level=1: best bid/ask with sizes, mid price, spread, and spread_bps. level=2 adds top-of-book depth (depth param, 1-50 price levels per side, default 20). Real-time from Coinbase. Use for trading signals, spread monitoring, liquidity checks, and execution decisions.

Paid endpoint: $0.004 per call via the x402 protocol (USDC on Base). An unpaid request returns 402 with payment requirements in the PAYMENT-REQUIRED response header; attach payment and retry.