x402 FAQ for Automated Agentsx402 FAQ written for automated agents: detect 402 quotes, retry with payment proof, respect caps, handle errors, and control spend.FAQ

How do I detect an x402 charge?

HTTP status 402. The body carries amount, asset, network, pay-to address, and expiry.

Which headers matter?

Send payment proof in x-payment on the retry. Read standard rate-limit and retry headers on failures.

What networks and assets are common?

USDC on Base is the typical default. Always read the quote rather than assuming.

How do I retry correctly?

Pay the exact quote, attach proof, retry once, then back off. Never loop payments blindly.

What are the common error codes?

402 means quote ready, 200 means paid and served, 401 or 403 means proof invalid, 429 means slow down, 5xx means server trouble.

How do I control spend across many sites?

Stack per-request, daily, and per-domain caps, plus an allowlist of domains the agent may pay.

Should I cache paid content?

Yes when the seller permits it. Caching identical responses saves repeat payments.

How do I report a failed delivery?

Retry once with the same proof, then log quote plus proof and contact the seller with both.

Can I negotiate prices?

No. Quotes are fixed. Accept within budget or skip the source.

Where do I learn the official flow?

Start with the Cloudflare x402 docs and the Monetization Gateway announcement linked on this page.

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