HTTP-native payments.

LX-402 is Loxley’s HTTP payment protocol. A caller signs an intent describing the purchase; a facilitator submits settlement. The merchant supplies a payout address, not a customer’s private key.

1. 01

   Request

   An unpaid request receives a 402 challenge with the asset, recipient, amount, and expiry.

2. 02

   Authorize

   The caller checks its spending policy, signs, then retries with the payment header.

3. 03

   Settle

   For the default fixed-price flow, settlement precedes the handler. The response includes a receipt.

Upstream specifies Node.js 20+. Prepare a dedicated test wallet, supported test tokens, and verified network and contract settings. The snippets below show the documented SDK interfaces; they are not standalone, verified installation instructions.

1. Inspect the facilitator

# Read-only checks. These do not sign or transfer anything.
curl https://loxley-facilitator-production.up.railway.app/health
curl https://loxley-facilitator-production.up.railway.app/supported

2. Protect an endpoint

// Illustrative middleware configuration, not a deployed Apiary route.
import { loxley } from '@loxley/server';

// app: your Express application.
// treasuryAddress and testAsset: verified TESTNET addresses.
// tokenName and tokenVersion: the test token's EIP-712 domain values.
app.get('/v1/report/:symbol', loxley({
  price: 10_000n, // 0.01 tokens only when the asset has 6 decimals
  payTo: treasuryAddress,
  asset: testAsset,
  assetName: tokenName,
  assetVersion: tokenVersion,
  network: 'eip155:46630',
  settlement: '0x54A49180CFb0f1573f8d6227eA36aDE583Cf0743',
  facilitator: 'https://loxley-facilitator-production.up.railway.app',
}), (req, res) => {
  res.json({ paidBy: req.loxley!.payer });
});

3. Give the caller a spending policy

// Illustrative SDK usage; package access is required first.
import { createLoxleyFetch } from '@loxley/client';

// account: a local signer for a dedicated TEST wallet.
// chain: the Robinhood Chain Testnet definition (46630).
// testAsset: a supported test-token address, verified independently.
const paidFetch = createLoxleyFetch({
  account,
  chain,
  policy: {
    maxAmountPerRequest: 50_000n,
    maxTotalPerSession: 1_000_000n,
    allowedAssets: [testAsset],
    allowedNetworks: ['eip155:46630'],
  },
});

// Use an endpoint that explicitly supports LX-402, not Apiary's gateway.
const response = await paidFetch('https://api.example.com/v1/report/AAPL');
console.log(response.headers.get('X-Loxley-Receipt'));

Limits are token base units, not dollar amounts. Keep signing keys local, use a dedicated wallet, and restrict assets and networks. Do not send LX-402 payment headers to Apiary’s existing x402 gateway.

Each accepted requirement defines the scheme, network, settlement contract, token, amount, recipient, salt, validity window, and available sources. Token-domain signing also needs the asset’s EIP-712 name and version.

The intent must match the selected requirement. Validate the recipient, token, amount, network, contract, expiry, and resource hash before accepting it. A fresh 32-byte salt distinguishes each challenge; upstream recommends a short 30–120 second validity window.

Only use sources advertised by the selected facilitator. Initial approvals and deposits are separate on-chain actions and can require gas. The documented browser paywall uses Permit2, not the authorization source.

The exact scheme authorizes a fixed charge. The upto scheme authorizes a ceiling, with the merchant reporting actual usage through req.loxleyMeter.charge().

Metered authorization is checked before work begins; settlement happens after the response. Spending limits must cover the full ceiling. The documented contract rejects charges above it, applies the fee to actual usage, and makes no charge if usage is not reported.

canonical = "<METHOD> <scheme>://<host><path>"
resourceHash = keccak256(utf8(canonical))
// Query parameters and fragments are excluded.

Recompute the resource hash when validating a request. Behind a reverse proxy, configure the middleware’s public origin so the client and merchant agree on the URL.

The documented hash does not bind the query string or request body. For prices that depend on parameters, issue distinct challenges and validate the application-level request terms; do not assume the path hash protects every input.

Upstream also documents Express middleware, a withLoxley Web Request/Response guard, and loxleyHono. Keep real SDK identifiers unchanged when integrating; Apiary branding does not rename these packages.

The read-only checks on October 1, 2026 returned a healthy facilitator advertising Robinhood Chain Testnet (eip155:46630), both schemes, all four sources, and feeBps: 30 (0.30%). This is a dated observation, not an uptime or future pricing guarantee.

Public facilitator

https://loxley-facilitator-production.up.railway.app

Advertised testnet settlement contract

0x54A49180CFb0f1573f8d6227eA36aDE583Cf0743

Discovery results can become stale; check a fresh challenge before paying. Registration in this index does not publish a service in Apiary’s marketplace. Request and response schemas beyond this overview remain in the upstream reference.

Loxley marks this implementation as unaudited and for testnet use. We checked public HTTP responses and package availability, not contract security, end-to-end SDK execution, or mainnet deployments.

• Use test funds only. Verify contracts, token domains, approvals, and spending limits independently.
• Signature binding and on-chain replay protection are the upstream design; they are not an independent security audit.
• A facilitator can fail or refuse service. A successful verification is not proof that a payment settled.
• Self-hosting requires gas on each configured chain. The source requires Postgres coordination before running multiple replicas; rate limits remain per process.
• Solana support is described as a design, not an implemented payment path. Do not infer live support from a network list.

Before an Apiary integration can be considered, confirm SDK access, review the contracts and commercial terms, and test payment, replay, failure, and recovery paths. This documentation does not activate LX-402 billing or replace existing marketplace payments.