x402 turns the long-dormant HTTP 402 "Payment Required" status into a real protocol for agents to pay for what they use.
With x402, a metered endpoint answers an unpaid request with a spec-exact 402 describing how to pay (amount, asset, network, address). The client — often an autonomous agent — pays (for example, USDC on Base via an EIP-3009 authorization) and retries with a payment header. The server verifies, settles, and serves. No accounts, no cards, no human.
x402 handles paying; a warrant handles permission to pay. Give an agent a warrant with a spend cap and it can transact autonomously over x402 while remaining strictly bounded — and every payment is recorded in the audit log. Liceat's gateway speaks x402 for metered calls out of the box.
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