How do AI agents pay for APIs and data?
AI agents pay per call in stablecoin over the x402 protocol: the server returns HTTP 402 with payment requirements, the agent's wallet signs an on-chain payment proof, and the server delivers the resource in the same request.
There are three viable patterns today: human-issued API keys plus monthly invoicing (legacy), agent-controlled credit cards (operationally hard), or HTTP-native micropayments. The third option, x402, is what Sella is built on.
In practice: an agent calls search_catalog (free, returns ranked listings with quality evidence). It picks one, inspects it with get_listing, and calls get_dataset. Sella returns HTTP 402 with the price and recipient. The agent's wallet signs a USDC payment, the agent retries with the signature attached, Sella verifies on-chain via the x402 facilitator, and the full dataset is returned. Settlement adds seconds, not minutes.