Multi-source volume-weighted median (VWM) spot price for 16 crypto assets (BTC/ETH/SOL/BNB/XRP/DOGE/ADA/AVAX/LINK/DOT/LTC/TRX/BCH/ATOM/NEAR/APT). Aggregates Binance, Coinbase, Kraken, and OKX in parallel (2 s timeout per source). Includes 1% outlier rejection, cross-exchange spread %, confidence grading (high/medium/low), and per-source USD volume weights. Kaiko-style reference pricing — $0.001/call.