x402 FAQ

What makes x402 different from a normal payment gateway?

x402 uses HTTP 402 Payment Required as part of the product flow, so payment requirements and protected delivery are described in the same protocol interaction.

What makes x402 different from a simple wallet transfer?

A simple transfer only moves value. x402 adds delivery semantics, payment state, and settlement verification so an app or API can decide when to unlock the protected response.

Is HTTP 402 an error?

No. For signed POST /api/v1/orders, HTTP 402 is the expected success path because the backend is returning payment requirements rather than the final protected content. Hosted QuickPay session creation returns 200.

Which mode should I choose first?

Start with DIRECT — it is the standard mode and covers almost every integration. Hosted QuickPay can run without merchant API keys; API keys are required for programmatic x402.

Does x402 support testnet integration?

Yes. x402 supports separate test and production environments with separate merchant credentials and supported payment configuration. See Developer Quick Start for the current production and test environment endpoints.

Use the API URL, merchant ID, API key, API secret, supported tokens, and payment chains issued for the environment you are integrating with.

When should I use DELEGATE?

Use DELEGATE only when payment must trigger on-chain logic or when the settlement flow requires delegated infrastructure rather than a simple direct payment path. DELEGATE is a separate payment mode available on request: it is disabled by default — contact the platform to enable it, subject to an eligibility and compliance review — and it may be restricted or unavailable in some jurisdictions. It requires API keys — integrate it via signed create-order or signed hosted checkout — plus a Bob-authorized MerchantCallback, and it is not available through the no-key QuickPay flow or Machine Payments Protocol (MPP).

How does x402 relate to agents?

x402 is a natural fit for agents because it gives them a machine-readable way to charge for API calls, workflow execution, or premium endpoints.

How does x402 relate to ERC-8004?

ERC-8004 is a trust and discovery layer. x402 is a payment and monetization layer. They complement each other rather than replacing one another.

Does x402 replace Bitcoin-backed settlement?

No. x402 is the payment rail for EVM payment flows, settlement verification, and callback execution paths.

What should I persist for audits?

Keep order identifiers, settlement proofs, and any internal delivery records required by your product or compliance model.

Where should I start if I am using AgentKit?

Start with AgentKit x402 Payments, then come back to the protocol pages if you need lower-level merchant or API detail.