Payments (x402)

Lucid uses x402 (HTTP 402) as its payment enforcement mechanism. Agents pay for services with USDC on any supported chain. The gateway never holds funds — facilitators handle all on-chain verification. Payments go 100% to the API provider.

How It Works

Agent sends a request without a payment proof
Gateway checks for a PayStream session credit — if available, debit and proceed
If no session, returns HTTP 402 with payment options (one per chain per facilitator)
Agent selects a chain, pays USDC on-chain, retries with proof header
X-Payment-Proof carries the tx hash; X-Payment-Chain specifies the chain
SpentProofsStore prevents replay (10-minute TTL)
Facilitator verifies the payment
If overpayment occurs, excess becomes PayStream session credit

Supported Chains

Chain	Type	USDC Address
Base	EVM	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`
Ethereum	EVM	`0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48`
Arbitrum	EVM	`0xaf88d065e77c8cC2239327C5EDb3A432268e5831`
Optimism	EVM	`0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85`
Polygon	EVM	`0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359`
ApeChain	EVM	`0xA2235d059F80e176D931Ef76b6C51953Eb3fBEf4`
Monad	EVM	`0x754704Bc059F8C67012fEd69BC8A327a5aafb603`
Solana	Solana	`EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v`
Sui	Move	`0xdba34...::usdc::USDC`

Using @lucid-fdn/pay

The @lucid-fdn/pay package provides a drop-in fetch() wrapper that auto-handles 402 responses:

import { payFetch } from '@lucid-fdn/pay';

// Automatically handles the 402 payment flow
const response = await payFetch('https://api.provider.com/v1/chat', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ model: 'gpt-4o', messages: [...] }),
});

Enabling Payments (API Providers)

API providers enable x402 on their tenant via the control plane:

curl -X PUT https://control-plane.lucid.foundation/admin/tenants/my-tenant/payment \
  -H "X-Admin-Key: ..." \
  -d '{
    "enabled": true,
    "defaultPrice": "0.01",
    "payoutAddress": "0x...",
    "acceptedTokens": ["USDC"],
    "acceptedChains": ["base", "ethereum", "solana"],
    "payStreamEnabled": true
  }'

Key Features

Feature	Description
PayRoute	Intelligent multi-facilitator routing — weighted scoring (gas 40%, latency 30%, success 20%, preference 10%)
PayStream	Session credit balances — deposit once, call many times with zero per-call gas
PayCascade	Composable multi-hop revenue pipelines — BPS-based splits across model/compute/tool/protocol
PayReputation	Agent credit scoring from receipt history — tiers: unverified, bronze, silver, gold, platinum
Zero-Config	One API call enables payment enforcement on all routes

Facilitators

Facilitator	Chains	Method
Direct	Base, Monad	On-chain EVM RPC (`eth_getTransactionReceipt`)
Coinbase	EVM	Coinbase x402 API
PayAI	Base, Ethereum, Arbitrum, Solana, Monad	PayAI API + RPC fallback
Sui	Sui	Sui RPC verification
Thirdweb	14 EVM chains	Thirdweb API + ERC-3009 signed authorizations

Execution Layer

Coordination Layer

Settlement Layer

Payments (x402)

How It Works

Supported Chains

Using @lucid-fdn/pay

Enabling Payments (API Providers)

Key Features

Facilitators

​How It Works

​Supported Chains

​Using @lucid-fdn/pay

​Enabling Payments (API Providers)

​Key Features

​Facilitators

How It Works

Supported Chains

Using @lucid-fdn/pay

Enabling Payments (API Providers)

Key Features

Facilitators