@untitledfinancial/dpx-x402

Gate any API endpoint behind USDC micropayments on Base mainnet. Agents pay automatically — no account, no API key, no subscription.

npm install @untitledfinancial/dpx-x402

How it works

An agent calls your endpoint. If no payment is attached, your server returns a 402 Payment Required with USDC payment details. The agent signs an EIP-3009 transfer from its funded wallet, retries with the X-Payment header, and your server verifies and responds. The entire loop is machine-to-machine — no human approves anything.

Agent → GET /your-endpoint
Server → 402: { amount: "150000", asset: USDC, payTo: "0x..." }

Agent signs EIP-3009 TransferWithAuthorization
Agent → GET /your-endpoint  (X-Payment: <signed token>)
Server verifies → 200: { your data }  (X-Payment-Response: receipt)

Cloudflare Workers / Hono

import { Hono } from 'hono'
import { DPX } from '@untitledfinancial/dpx-x402/hono'

const app  = new Hono()
const dpx  = DPX.create({
  recipient: '0xYourWalletAddress',
  secretKey: process.env.DPX_SECRET_KEY!,
})

// Gate a route — $0.15 USDC per call
app.get('/signal', dpx.hono.charge({ amount: '0.15' }), (c) =>
  c.json({ regime: 'STABLE', score: 42 })
)

export default app

Next.js App Router

// app/api/signal/route.ts
import { DPX } from '@untitledfinancial/dpx-x402/nextjs'

const dpx = DPX.create({
  recipient: '0xYourWalletAddress',
  secretKey: process.env.DPX_SECRET_KEY!,
})

export const GET = dpx.charge({ amount: '0.15' })(() =>
  Response.json({ regime: 'STABLE', score: 42 })
)

Express / Node.js

import express from 'express'
import { DPX } from '@untitledfinancial/dpx-x402/express'

const app = express()
const dpx = DPX.create({
  recipient: '0xYourWalletAddress',
  secretKey: process.env.DPX_SECRET_KEY!,
})

app.get('/signal', dpx.node.charge({ amount: '0.15' }), (req, res) => {
  res.json({ regime: 'STABLE', score: 42 })
})

Manual mode (raw Fetch API)

import { DPX } from '@untitledfinancial/dpx-x402'

const dpx = DPX.create({
  recipient: '0xYourWalletAddress',
  secretKey: process.env.DPX_SECRET_KEY!,
})

export async function handler(request: Request): Promise<Response> {
  return dpx.charge({ amount: '0.15' })(
    () => Response.json({ regime: 'STABLE', score: 42 })
  )(request)
}

Configuration

DPX.create({
  // Required
  recipient:  '0x...',               // Address that receives USDC payments
  secretKey:  process.env.SECRET!,   // Secret for signing receipts — never expose

  // Optional
  currency:   '0x833589...',         // USDC on Base (default). Override for EURC or other tokens.
  network:    'base',                // 'base' (default) or 'base-sepolia' for testnet
  waitForConfirmation: true,         // Wait for on-chain confirmation (default: true)
                                     // Set false for lower latency (optimistic)
})

Per-route overrides

// Different amount, currency, or recipient per route
dpx.charge({
  amount:    '0.75',
  currency:  '0x...',      // e.g. EURC for EUR-denominated routes
  recipient: '0x...',      // e.g. per-product wallet
})

Payment methods

By default, dpx-x402 accepts USDC on Base mainnet via EIP-3009 TransferWithAuthorization. This is the same mechanism used by DPX Intelligence and all x402-gated DPX endpoints.

Any agent with a funded Base wallet can pay immediately — no new token, no onboarding.

Testnet

Set network: 'base-sepolia' and fund your agent wallet with testnet USDC from the Circle faucet.

What the agent receives

Every verified response includes an X-Payment-Response header:

{
  "paid": true,
  "from": "0x<agent-wallet>",
  "to": "0x<your-wallet>",
  "amount": "0.15",
  "currency": "0x833589...",
  "network": "eip155:8453",
  "verifiedAt": "2026-07-25T14:00:00Z"
}

Agent-side: paying with dpx-x402

If you are building the agent side (the caller), see:

• DPX Intelligence docs — example x402 signing code in Python
• x402 protocol reference — full EIP-3009 flow

Discovery

After your server is running, add a GET /openapi.json endpoint so agents can discover your API and its payment terms. Tag paid routes with x-payment-info:

{
  "paths": {
    "/signal": {
      "get": {
        "x-payment-info": {
          "offers": [{ "amount": "0.15", "currency": "USDC", "network": "base" }]
        }
      }
    }
  }
}

License

Business Source License 1.1 — see LICENSE.

Built by Untitled_ LuxPerpetua Technologies, Inc.