PipRail

Monetize anything. Pay for anything.

PipRail is the open payment layer for autonomous software. It turns the long-dormant HTTP 402 Payment Required status into a real, universal rail: an agent can spin something up and charge for it in one line, and another agent can pay for it on its own — no platform to ask, no middleman to pay, no account to create. Just npm install, name a chain, add a wallet.

Monetize anything

Wrap any route, API, dataset, or model and it charges per call — paid straight to your wallet. An agent can build something and start earning the same minute, with no fee and no backend.

Agents that pay their own way

Hand an LLM a budget-bound wallet and it discovers, quotes, plans, and pays x402 URLs autonomously — capped by a spend policy it cannot exceed. The agent economy needs money that moves at machine speed; this is it.

Machine-to-machine marketplaces

Agents find each other’s paid services on the open indexes, price them, and settle peer-to-peer. A universal adapter across every major chain — one chain: parameter picks the rail.

Programmable money, self-custodial

Every payment is a real on-chain transfer, verified locally against your own RPC. No custody, no hosted facilitator, no toll booth — the rail is open and free, the way the agent economy should run.

Take a payment — one line

import express from 'express'
import { requirePayment } from '@piprail/sdk'

const app = express()

// This route now costs 0.10 USDC on Base — paid straight to your wallet.
app.get(
  '/report',
  requirePayment({ chain: 'base', token: 'USDC', amount: '0.10', payTo: '0xYourWallet' }),
  (req, res) => res.json({ report: 'the goods' }),
)

app.listen(3000)

The first request gets a 402 with payment instructions; once the caller pays on-chain, the request goes through. You didn’t paste a token address, run a server, deploy a contract, or sign up for anything.

→ Accepting payments

Pay a payment — wrap fetch

import { PipRailClient } from '@piprail/sdk'

const client = new PipRailClient({
  chain: 'base',
  wallet: { privateKey: process.env.AGENT_KEY },
})

// Identical to fetch — but if the URL answers 402, it pays and retries automatically.
const res = await client.fetch('https://api.example.com/report')
const data = await res.json()
// → the unlocked response body, exactly as the resource served it

→ Making payments

One rail, every chain

Every major EVM chain plus Solana, TON, Tron, NEAR, Sui, Aptos, Algorand, Stellar, and the XRP Ledger — one chain parameter picks everything. USDC almost everywhere, USDT on most, the native coin on every family, and any other token by address. No allowlist: pass any EVM chain by { id, rpcUrl }.

requirePayment({ chain: 'base',   token: 'USDC', amount: '0.10', payTo }) // USDC on Base
requirePayment({ chain: 'solana', token: 'USDC', amount: '0.10', payTo }) // USDC on Solana
requirePayment({ chain: 'tron',   token: 'USDT', amount: '1',    payTo }) // USD₮ on Tron

→ Browse every chain

Two packages, no server

@piprail/sdk

The TypeScript SDK — requirePayment to charge, PipRailClient to pay. Runs headless or in the browser. Spend budgets, gas estimates, planPayment, and discovery built in.

Read the SDK docs →

@piprail/mcp

A Model Context Protocol server that hands Claude, Cursor, or any MCP agent a budget-bound wallet — add one env block and it pays x402 URLs on its own, within caps it can’t exceed.

Set up the MCP server →

Start here

Introduction What PipRail is, and the one idea that makes it work.

Quickstart Gate a route and pay a 402 end-to-end in five minutes.

How it works The 402 round-trip and merchant-local verification — no facilitator.

Built for agents Hand an LLM a wallet it can spend, safely.