x402 Payment-Required Flow

Agent pays per request over HTTP 402 with a stablecoin, settled onchain by a facilitator

x402 Payment-Required Flow Agent pays per request over HTTP 402 with a stablecoin, settled onchain by a facilitator GET /paid-resource 402 + payment instructions amount, asset, recipient, network retry + signed payment proof agent signs a stablecoin tx offchain verify payment settle stablecoin transfer confirmed onchain valid + settled 200 + data Request + 402 Sign + retry Verify + settle Return data Agent · wallet key holder · Sequence participant Agent wallet key holder Server · paid API · Sequence participant Server paid API Facilitator · verify + settle · Sequence participant Facilitator verify + settle Blockchain · stablecoin ledger · Sequence participant Blockchain stablecoin ledger Legend request return security async trace

Main path

  • • Request, 402 challenge, signed retry, then data
  • • No login, card, or subscription account
  • • Whole cycle completes in seconds

Facilitator role

  • • Verifies the attached payment proof
  • • Settles the stablecoin transfer onchain
  • • Server releases data only after settlement

Why it fits agents

  • • Machine-readable terms, no human in the loop
  • • Stablecoins keep tiny per-call amounts economical
  • • Onchain finality means no chargebacks

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