How It Works

FX402 implements a renting and licensing flow atop the x402 payment protocol.
It introduces a new profile — R402 — describing how time-based usage rights are offered, paid for, and verified.

🔁 Lifecycle Overview

Every R402 transaction follows a three-step cycle:

1. Request → 402 Payment Required

A client requests access to a protected resource.


GET /nft/rare-001.png

The server responds with an HTTP 402 Payment Required, including a JSON payload that defines rental options and terms:


{
  "standard": "x402",
  "profile": "r402/v1",
  "usage": {
    "tiers": [
      { "id": "1d", "price": { "amount": "0.50", "currency": "USDC", "chain": "solana" } },
      { "id": "7d", "price": { "amount": "2.00", "currency": "USDC", "chain": "solana" } }
    ],
    "modes": ["view", "remix"]
  },
  "pay_to": { "address": "SoLWallet111...", "chain": "solana" },
  "facilitator": "https://facilitator.fx402.xyz/settle"
}

2. Payment → Verification

The client (or SDK) selects a tier, completes payment to the specified wallet or facilitator, and provides proof of payment in a follow-up request:


{
  "standard": "x402",
  "profile": "r402/v1",
  "tier_id": "7d",
  "payment_proof": {
    "chain": "solana",
    "currency": "USDC",
    "tx": "4sJQd2cA...FyW"
  }
}

The server or facilitator verifies this proof (on-chain or via a settlement endpoint).

3. Unlock → Receipt Issued

Upon successful verification, the server delivers the resource and issues a signed receipt to the client:


{
  "profile": "r402/v1",
  "receipt": {
    "resource": "nft:solana:mint:9abc...xyz",
    "tier_id": "7d",
    "paid": { "amount": "2.00", "currency": "USDC" },
    "valid_from": "2025-10-29T00:00:00Z",
    "valid_until": "2025-11-05T00:00:00Z",
    "jwt": "<signed JWT>"
  }
}

This receipt serves as a portable license — the user can re-present it for access until expiry.

🧱 Core Components

Component	Role
Client / SDK	Handles requests, displays pricing, processes payment, and retries after payment
Server	Defines tiers/rights, verifies payment, issues receipts, serves the asset
Facilitator (opt.)	Independent service for payment validation, replay protection, and receipt signing
Blockchain Layer	Confirms transactions (Solana USDC as first supported chain)

⚙️ Implementation Paths

Honor-System Mode: Pure HTTP; minimal infra.
Verified Mode: Facilitator validates all payments, signs JWT receipts.
Hybrid Mode: Short-term/low-value rentals are honor-based; high-value are fully verified.