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In b402, the facilitator is a trust-minimized and off-chain service that handles the verification and settlement of payments between agents (clients) and service providers (servers). It serves as the connective tissue between HTTP-level requests and on-chain execution.

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What is a Facilitator?

A facilitator is an independent service that:
  • Verifies the validity of payment payloads submitted by clients.
  • Settles payments or identity proofs on-chain on behalf of servers.
By using a facilitator, servers can accept crypto-native payments without needing direct blockchain infrastructure or custom verification logic. This design keeps b402 integrations light, fast, and modular.

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Facilitator Responsibilities

  • Verify payments: Confirm that the client’s submitted payload satisfies the server’s declared payment terms.
  • Settle transactions: Post valid transactions to the blockchain and monitor for confirmation.
  • Provide signed responses: Return structured verification and settlement responses that the server can use to authorize access.
The facilitator never holds user funds or keys. It simply verifies signatures, executes transactions, and returns proofs of settlement.

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Why Use a Facilitator?

Using a facilitator simplifies the integration process for service providers and ensures protocol-level consistency:
  • Reduced complexity: No need to maintain blockchain nodes or custom verification code.
  • Standardized flows: Shared verification and settlement semantics across all b402 integrations.
  • Faster onboarding: Start accepting payments instantly without blockchain-specific logic.
  • Scalable trust model: Facilitators can be public, private, or self-hosted, depending on your architecture.
While verification can be implemented locally, using a facilitator provides uniform behavior across the network and simplifies adoption.

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Live Facilitators

The official b402 Facilitator is currently live on BNB Chain mainnet and testnet, supporting BNB, USDT, USD1, and a growing list of BEP-20 tokens. See the Facilitator guide for architecture details and integration examples. We encourage community partners, node operators, and infrastructure teams to deploy their own facilitators to extend coverage across regions and networks.
Additional endpoints will be listed here as the ecosystem evolves.

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Interaction Flow

Below is the typical end-to-end process for verification and settlement in b402:
  1. Client (agent) sends an HTTP request to a b402-enabled resource server.
  2. Server responds with 402 Payment Required, including structured payment details (amount, token, recipient, scheme).
  3. Client constructs a signed payment payload according to the chosen scheme.
  4. Client resends the request with an X-PAYMENT header containing the payload.
  5. Server forwards the payload and payment details to the facilitator via the /verify endpoint.
  6. Facilitator validates the payload using the specified scheme and network parameters.
  7. Facilitator returns a verification response (valid or invalid) to the server.
  8. Server, upon valid verification, fulfills the request and optionally calls /settle to finalize payment.
  9. Facilitator executes the on-chain settlement transaction and waits for confirmation.
  10. Facilitator returns a Payment Execution Response containing settlement metadata.
  11. Server returns 200 OK with the requested resource and an X-PAYMENT-RESPONSE header containing encoded settlement data.