open402

HTTP finally gets paid.

HTTP has reserved the 402 Payment Required status code since 1991. open402 makes it real — a simple, open protocol and TypeScript SDK that lets any server charge per-request and any client pay transparently, without subscriptions, API keys, or intermediaries.

How it works

1. Client requests a resource
2. Server responds 402 Payment Required with payment headers
3. Client creates an invoice via POST /.well-known/402/pay
4. Client pays via their wallet
5. Client polls until receipt is ready
6. Client retries with Payment-Receipt: <jwt>
7. Server responds 200 OK

Quick Start

Server (Express)

import express from 'express'
import { Open402Server, createWellKnownRouter, paywall } from '@open402/server'

const app = express()
app.use(express.json())

const pay402 = new Open402Server()
await pay402.init()

// Register a payment adapter
pay402.registerAdapter(myLightningAdapter)

// Mount well-known routes
app.use('/.well-known/402', createWellKnownRouter(pay402))

// Add a paywall to any endpoint
app.get(
  '/api/data',
  paywall(pay402, { path: '/api/data', amount: 1000, currency: 'BTC' }),
  (req, res) => res.json({ secret: 'the data' }),
)

Client

import { Open402Client } from '@open402/client'
import { WebLNWallet } from '@open402/lightning'

const client = new Open402Client({ wallet: new WebLNWallet() })

// Automatically handles 402, pays, and retries
const res = await client.fetch('https://api.example.com/api/data')
const data = await res.json()

Packages

Package	Description
@open402/core	Protocol types, header parser, JWT receipts, discovery
@open402/server	Express middleware, well-known routes, paywall()
@open402/client	Open402Client with auto-pay and receipt caching
@open402/lightning	Lightning Network adapters (LND + WebLN)

Protocol

The open402 protocol is language-agnostic. See spec/open402.md for the full RFC — implementable in any language.

Run the Example

# Terminal 1 — server
cd apps/example && pnpm server

# Terminal 2 — client
cd apps/example && pnpm client

Development

pnpm install
pnpm test       # run all tests
pnpm build      # build all packages

Contributing

open402 is MIT licensed. Payment adapter contributions welcome — implement the PaymentAdapter interface for any payment method.