Anyone, permissionless. Your MetaMask signs the payment authorization — your key never leaves the extension, and we never see it. Settlement runs on USDC (Base) via the x402 rail.
Subject id:
terms appear here (amount, pay-to, offer receipt)
result appears here — verify it at /gspc-verify
Agents: this same rail is machine-payable — 402 carries extensions.bazaar input/output schemas and a signed offer receipt. SDK: @csoai/x402.