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Agents often need to pay for services—API calls, data access, compute—without a human approving each payment. HTTP 402 Payment Required is designed for this: when the agent calls a 402-protected API, the server returns payment requirements; the agent pays and retries; the server delivers the resource. Dynamic server wallets provide the signing and key management layer. The wire format and settlement depend on which protocol you use.

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Integration paths

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x402

The x402 protocol defines how onchain payment is negotiated over HTTP. The client receives payment requirements in the 402 response, signs with its wallet, and retries the request with an X-Payment header. A facilitator (for example, Coinbase Developer Platform) verifies and settles onchain. Best for: x402-protected APIs, zero-fee USDC payments on Base, CDP-style facilitators.

Using Dynamic with x402

Wire up a Dynamic server wallet as the x402 payment client.

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Tempo MPP

Tempo’s Machine Payment Protocol (MPP) extends HTTP 402 for machine-to-machine traffic. The mppx client handles negotiation, signing, and retry automatically. Dynamic’s Node SDK provides the MPC-backed signing account. Best for: APIs and services that target Tempo’s network, machine-to-machine payments on Tempo Moderato.

Machine Payments on Tempo (Node.js)

Create a Dynamic server wallet, fund it, and make MPP payments to 402-protected APIs.

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Choosing between x402 and Tempo MPP

x402Tempo MPP
Protocolx402MPP
SettlementOnchain (Base, USDC)Tempo network
Client libraryx402-fetch, x402-axiosmppx
FacilitatorCDP (and others)Tempo
For a full comparison and background on how 402 flows work, see the HTTP 402 overview.