Vanta SDK - x402-native payments for APIs, agents, and apps

Example Repositories

Clone and run these full example projects to see Vanta SDK in action:

Express Basic

Simple Express server with payment-protected endpoints.

Next.js API Routes

Payment middleware with Next.js App Router and API routes.

AI Agent Integration

Autonomous agent that pays for API access with budget controls.

Metered API

Usage-based billing with quota management and prepaid credits.

Minimal Server Example

The simplest possible server with a payment-protected endpoint:

server.ts

import express from 'express'
import { VantaMiddleware } from '@vanta/middleware'

const app = express()

const paywall = VantaMiddleware({
  price: '0.001',
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
})

app.get('/api/data', paywall, (req, res) => {
  res.json({ secret: 'premium data', timestamp: Date.now() })
})

app.listen(3000, () => console.log('Server on :3000'))

Minimal Client Example

The simplest client that handles 402 responses automatically:

client.ts

import { VantaClient } from '@vanta/client'
import { ethers } from 'ethers'

const provider = new ethers.BrowserProvider(window.ethereum)
const client = new VantaClient({ provider })

// This will prompt for payment if needed
const response = await client.fetch('http://localhost:3000/api/data')
const data = await response.json()
console.log(data)

Token-Based Access Pattern

Issue tokens after payment for session-based access:

token-server.ts

import express from 'express'
import { VantaMiddleware, VantaTokenIssuer } from '@vanta/middleware'

const app = express()

const tokenIssuer = new VantaTokenIssuer({
  secret: process.env.TOKEN_SECRET!,
  expiresIn: '1h',
})

const paywall = VantaMiddleware({
  price: '0.01',
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
  onPaymentVerified: async (payment, req, res) => {
    const token = await tokenIssuer.issue(req)
    res.setHeader('X-Vanta-Token', token)
  },
})

// Use token or payment
const auth = tokenIssuer.middleware({ fallback: paywall })

app.get('/api/premium/*', auth)

app.get('/api/premium/data', (req, res) => {
  res.json({ data: 'premium', user: req.vanta?.claims })
})

app.listen(3000)

Webhook Notification Pattern

Notify external systems when payments are received:

webhook-server.ts

import express from 'express'
import { VantaMiddleware } from '@vanta/middleware'

const app = express()

const paywall = VantaMiddleware({
  price: '0.001',
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
  onPaymentVerified: async (payment, req) => {
    // Notify your backend
    await fetch('https://your-api.com/webhooks/payment', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        txHash: payment.transactionHash,
        amount: payment.amount,
        from: payment.from,
        endpoint: req.path,
        timestamp: new Date().toISOString(),
      }),
    })
  },
})

app.get('/api/data', paywall, handler)

Multi-Tier Pricing Pattern

Different prices for different endpoints or features:

tiered-server.ts

import express from 'express'
import { VantaMiddleware } from '@vanta/middleware'

const app = express()

// Basic tier - cheap
const basicPaywall = VantaMiddleware({
  price: '0.0001',
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
  memo: 'Basic API Access',
})

// Premium tier - more expensive, more features
const premiumPaywall = VantaMiddleware({
  price: '0.01',
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
  memo: 'Premium API Access',
})

// Dynamic pricing based on request
const dynamicPaywall = VantaMiddleware({
  price: (req) => {
    const complexity = req.query.complexity || 'simple'
    const prices = { simple: '0.0001', medium: '0.001', complex: '0.01' }
    return prices[complexity as keyof typeof prices] || '0.001'
  },
  recipient: process.env.WALLET_ADDRESS!,
  network: 'base',
})

app.get('/api/basic/*', basicPaywall)
app.get('/api/premium/*', premiumPaywall)
app.get('/api/dynamic/*', dynamicPaywall)

app.listen(3000)

Examples