What is the Facilitator?

The facilitator is an off-chain service that verifies x402 payment proofs on behalf of resource servers. When a client attaches an X-Payment header to an HTTP request, the resource server does not query the blockchain directly — it forwards the proof to the facilitator, which performs on-chain verification and returns a signed confirmation.

Public endpoint: https://facilitator.canister.software

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Why a Facilitator?

On-chain verification from inside a request handler is impractical — it would block the server on RPC latency for every paid request, require the server to maintain full blockchain state or RPC credentials per network, and make multi-network support expensive to operate.

The facilitator solves this by acting as a stateless verification proxy. The resource server speaks a single REST protocol to one endpoint regardless of which network the client paid on. The facilitator resolves the chain-specific logic and returns a simple valid/invalid signal.

Resource Server          Facilitator                  Chain
      │                       │                          │
      ├── POST /verify ───────►│                          │
      │   { proof, expected }  │                          │
      │                        ├── RPC call (network) ───►│
      │                        │◄── transfer confirmed ───┤
      │◄── { valid: true } ────┤                          │

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Verification Flow

1. Client sends a request with X-Payment header containing a signed payment proof
2. Resource server extracts the proof and the expected payment parameters (network, amount, payTo)
3. Resource server calls the facilitator’s /verify endpoint
4. Facilitator queries the appropriate chain to confirm the transfer occurred
5. Facilitator returns { valid: true } or an error
6. Resource server either serves the response or returns 402 again

The facilitator is stateless — each call is an independent verification. The resource server does not maintain a session with it.

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Connecting a Resource Server

import { HTTPFacilitatorClient } from '@x402/core/server'

const facilitatorClient = new HTTPFacilitatorClient({
  url: process.env.FACILITATOR_URL ?? 'https://facilitator.canister.software'
})

Pass this client to x402ResourceServer. All verification calls from paymentMiddleware are routed through it automatically.

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Reference

Property	Value
Public URL	https://facilitator.canister.software
Client class	HTTPFacilitatorClient from @x402/core/server
Protocol	REST — resource server POSTs payment proofs, receives confirmation
Statefulness	Stateless — each verification is independent
Multi-network	Yes — the facilitator handles all supported networks behind one endpoint

See Supported Networks for the full list of chains and tokens the facilitator accepts.