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x402 escrow stack · Boson Protocol
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x402 escrow stack

x402b extends the x402 standard (in-band HTTP-402 payments) with non-custodial escrow on the Boson Diamond. A buyer requests a resource, gets a 402 Payment Required with a Boson escrow option, signs a meta-transaction, and the facilitator settles it on-chain. Funds release on redemption or dispute resolution.

Packages

PackageRoleReference
x402-coreSchemas, EIP-712 builders, state machine→
x402-evmCalldata builders for the two flows (deferred / atomic)→
x402-serverResource-server SDK (framework-agnostic)→
x402-server-expressExpress adapter(in package)
x402-clientBuyer-side SDK (framework-agnostic)→
x402-client-fetchFetch API adapter(in package)
x402-facilitatorReference relayer library→
x402-facilitator-expressExpress adapter(in package)
x402-fulfillmentPluggable fulfillment channels (inline · email · XMTP · webhook · IPFS)→
x402-actionsState machine + nextActions envelope→

Three actors

When to use x402

  • You sell access to an HTTP resource (API, file, model inference).
  • The buyer is an AI agent that needs in-band payment, not OAuth + Stripe.
  • You want non-custodial escrow without writing your own contracts.

If you're selling physical goods, use the Core SDK directly. If you're selling digital goods through a marketplace, use the SDK or MCP.

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