Public x402 facilitator for Base, Solana, and ICP

The facilitator is an off-chain service that verifies x402 payment proofs on behalf of resource servers. When a client attaches a signed payment to an HTTP request, the resource server does not query the blockchain directly: it forwards the payment to the facilitator, which verifies it and then settles it on chain.

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 verification and settlement service. 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, checks the payment, and then settles it on chain.

Resource Server               Facilitator                  Chain
      │                            │                          │
      ├── POST /verify ───────────►│                          │
      │   { paymentPayload,        │                          │
      │     paymentRequirements }  │                          │
      │◄── { isValid: true } ──────┤                          │
      │                            │                          │
      ├── POST /settle ───────────►├── submit transfer ──────►│
      │◄── { success, transaction }┤◄── confirmed ────────────┤

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Verification Flow

1. Client sends a request with a signed payment in the PAYMENT-SIGNATURE header (X-PAYMENT for x402 v1 clients)
2. Resource server pairs the payment with what the route expects: network, amount, and payTo
3. Resource server calls the facilitator’s POST /verify, which returns { isValid, invalidReason? }
4. If the payment is valid, the resource server calls POST /settle, and the facilitator submits the transfer on the payment’s network
5. Settlement returns { success, transaction, network }, or success: false with an errorReason
6. Resource server serves the response, or returns 402 again

paymentMiddleware from @x402/express makes these calls for you. Each call is independent; the resource server does not hold a session with the facilitator.

Endpoints

Route	Purpose
POST /verify	Check a payment against its requirements, without moving funds
POST /settle	Settle a verified payment on chain
GET /supported	The scheme and network pairs this facilitator handles
GET /info	Facilitator identity, including its ICP principal and enabled networks
GET /discovery/resources	A catalog of resources that accept x402 payment through this facilitator
GET /health	Liveness check

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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: the resource server posts each payment to /verify, then /settle
State	Each call is independent. The facilitator keeps a small database of used payment nonces, so a payment cannot be replayed, and of its discovery catalog
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.