x402 Tutorial: Pay-Per-Call APIs for AI Agents, No API Key Required

Описание и применение

Показано, как использовать протокол x402 для оплаты API по запросу без ключей, включая чтение 402‑ответа, подпись USDC и повторный запрос.

Задача

Agents need to use third‑party APIs without pre‑creating accounts or storing API keys, yet still pay per request.

Результат

Demonstrated how to inspect a 402 challenge, interpret payment terms, and pay with USDC to access services at $0.005 per call.

Рабочий процесс

• Send normal request to endpoint
• Receive 402 with PAYMENT-REQUIRED header
• Decode base64 JSON to get payment options
• Choose option and sign USDC transaction
• Retry request with PAYMENT-SIGNATURE header
• Server verifies payment and returns response with PAYMENT-RESPONSE header

Доказательства

The server answers an unpaid request with HTTP 402 Payment Required and a machine‑readable price.

Источник

Running it prints something like: exact on eip155:8453: $0.005 to 0xF732ea490c5766071785a2310523f7fA2CEbB829 MPP offered: True

Источник