@web3nz/glyde

Express middleware that paywalls API endpoints using the x402 protocol — AI agents pay per request in USDC on Avalanche, settled on-chain in ~2 seconds.

How it works

1. Create a product in the web3nz dashboard and copy the API key
2. Drop paywall.protect() onto any Express route
3. When an agent hits your endpoint with no payment, the middleware returns 402 Payment Required with your product's price and payment address — fetched automatically from the dashboard
4. The agent signs an EIP-712 TransferWithAuthorization off-chain (gasless for the agent) and retries
5. Middleware validates the signature, calls transferWithAuthorization() on the USDC contract
6. USDC moves directly from agent wallet → your wallet on-chain. Your handler runs.

The agent never needs AVAX for gas — your server pays gas from PAYWALL_PRIVATE_KEY.

Installation

npm install @web3nz/glyde

Prerequisites

• A product created in the web3nz dashboard with price and receiving wallet configured
• A wallet funded with AVAX on Avalanche C-Chain to pay gas for settlements
• PAYWALL_PRIVATE_KEY and RPC_URL environment variables set

Quick start

import express from 'express';
import { createPaywall } from '@web3nz/glyde';

const app = express();

// Pass your product API key from the web3nz dashboard
const paywall = createPaywall(process.env.PRODUCT_API_KEY!);

// Free endpoint — no payment required
app.get('/free', (req, res) => {
  res.json({ message: 'free content' });
});

// Paywalled — price and recipient set in dashboard
app.get('/premium', paywall.protect(), (req, res) => {
  res.json({ message: 'premium content' });
});

app.listen(3000);

API Reference

createPaywall(apiKey)

Creates a paywall instance. Fetches product config (price, recipient, network) from the web3nz dashboard on first request and caches it.

| Parameter | Type | Description | |---|---|---| | apiKey | string | Product API key from the web3nz dashboard |

Returns an object with a protect method.

paywall.protect()

Express middleware factory. Place before your route handler.

Without payment — returns 402:

{
  "x402Version": 1,
  "product": {
    "id": "prod_abc123",
    "name": "My API",
    "description": "Premium data endpoint"
  },
  "accepts": [{
    "scheme": "exact",
    "network": "avalanche-fuji",
    "maxAmountRequired": "10000",
    "resource": "/premium",
    "payTo": "0xYourWallet",
    "asset": "0x5425890298aed601595a70AB815c96711a31Bc65",
    "maxTimeoutSeconds": 60
  }],
  "error": "X-PAYMENT header is required"
}

With valid payment — calls next() and sets header:

X-PAYMENT-RESPONSE: {"txHash":"0x...","status":"confirmed"}

Environment variables

| Variable | Required | Description | |---|---|---| | PAYWALL_PRIVATE_KEY | Yes | Private key of wallet that submits on-chain txs (needs AVAX for gas) | | RPC_URL | Yes | Avalanche JSON-RPC endpoint | | DASHBOARD_BACKEND_URL | No | web3nz dashboard API base URL (default: http://localhost:3001) | | PRODUCT_CONFIG_CACHE_TTL_MS | No | Product config cache duration in ms (default: 30000) |

Supported networks

| Network | Chain ID | USDC Contract | |---|---|---| | avalanche-fuji (testnet) | 43113 | 0x5425890298aed601595a70AB815c96711a31Bc65 | | avalanche (mainnet) | 43114 | 0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E |

License

MIT