L402 Kit

l402-kit

Add Bitcoin Lightning pay-per-call to any API. 3 lines of code.

▶ Watch end-to-end demo — install → 402 → pay → 200 OK

Live traction

🇺🇸 Charge for your API in Bitcoin Lightning. 3 lines of code. 🇧🇷 Monetize sua API com Bitcoin Lightning. 3 linhas de código. 🇪🇸 Monetiza tu API con Bitcoin Lightning. 3 líneas de código. 🇨🇳 用 3 行代码，通过比特币闪电网络收费。 🇮🇳 अपने API को Bitcoin Lightning से 3 लाइनों में मोनेटाइज़ करें। 🇸🇦 اكسب من API الخاص بك عبر Bitcoin Lightning. 3 أسطر فقط. 🇫🇷 Monétisez votre API en Bitcoin Lightning. 3 lignes de code. 🇩🇪 Monetarisiere deine API mit Bitcoin Lightning. 3 Zeilen Code. 🇷🇺 Монетизируй свой API через Bitcoin Lightning. 3 строки кода. 🇯🇵 Bitcoin LightningでAPIを3行で収益化。 🇮🇹 Monetizza la tua API con Bitcoin Lightning. 3 righe di codice.

📖 Official docs: 🇺🇸 · 🇧🇷 · 🇪🇸 · 🇨🇳 · 🇮🇳 · 🇸🇦 · 🇫🇷 · 🇩🇪 · 🇷🇺 · 🇯🇵 · 🇮🇹

Install

npm install l402-kit        # TypeScript / Node.js / Express
pip install l402kit         # Python / FastAPI / Flask
go get github.com/shinydapps/l402-kit/[email protected]   # Go / net/http / Chi / Gin
cargo add l402kit           # Rust / axum

AI Agents / LLMs: See llms.txt for machine-readable instructions. Agent discovery: /.well-known/agent.json · /.well-known/l402.json

For AI Agents

l402-kit is the payment layer for autonomous agents. Agents can pay for APIs without human intervention.

System prompt snippet — add this to any agent to enable L402 payments:

You have access to paid APIs via the L402 protocol.
When you call an API that returns HTTP 402, use the L402Client from l402-kit
to pay automatically with Bitcoin Lightning.
Budget limit: {BUDGET_SATS} sats per session. Never exceed this limit.

Agent SDK quickstart:

import { l402Client, buildWallet } from "l402-kit/agent";

const client = l402Client({
  wallet: buildWallet(process.env), // auto-detects BLINK_API_KEY or ALBY_TOKEN
  budgetSats: 1000,
});

const data = await client.fetch("https://api.example.com/paid-endpoint");

MCP Server (for Claude Desktop, Cursor, and any MCP-compatible agent):

{
  "mcpServers": {
    "l402-kit": {
      "command": "npx",
      "args": ["l402-kit-mcp"],
      "env": { "BLINK_API_KEY": "your-key" }
    }
  }
}

Compatible with: LangChain · OpenAI Agents · CrewAI · Vercel AI SDK · AutoGPT · Any MCP client

Protocol support: L402 (Bitcoin Lightning) · x402 (USDC/Coinbase) compatible

How it works

1. Client calls your API
       ↓
2. API returns  HTTP 402 + BOLT11 invoice + macaroon
       ↓
3. Client pays  (any Lightning wallet, < 1 second, any country)
       ↓
4. Client sends Authorization: L402 <macaroon>:<preimage>
       ↓
5. API verifies SHA256(preimage) == paymentHash  ✓
       ↓
6. HTTP 200 OK + your data

── Fee flow (managed mode) ─────────────────────────────────
   Payment → 99.7% → your Lightning Address  (instant)
           →  0.3% → ShinyDapps

Quickstart

TypeScript

import express from "express";
import { l402, AlbyProvider } from "l402-kit";

const app = express();

const lightning = new AlbyProvider(process.env.ALBY_TOKEN!);

app.get("/premium", l402({ priceSats: 100, lightning }), (_req, res) => {
  res.json({ data: "Payment confirmed." });
});

app.listen(3000);

Python

from fastapi import FastAPI, Request
from l402kit import l402_required

app = FastAPI()

@app.get("/premium")
@l402_required(price_sats=100, owner_lightning_address="[email protected]")
async def premium(request: Request):
    return {"data": "Payment confirmed."}

Go

package main

import (
    "fmt"
    "net/http"
    l402kit "github.com/shinydapps/l402-kit/go"
)

func main() {
    http.Handle("/premium", l402kit.Middleware(l402kit.Options{
        PriceSats:             100,
        OwnerLightningAddress: "[email protected]",
    }, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintln(w, `{"data": "Payment confirmed."}`)
    })))
    http.ListenAndServe(":8080", nil)
}

Rust

use axum::{middleware, routing::get, Router};
use l402kit::{l402_middleware, Options};
use std::sync::Arc;

#[tokio::main]
async fn main() {
    let opts = Arc::new(Options::new(100).with_address("[email protected]"));

    let app = Router::new()
        .route("/premium", get(|| async { "Payment confirmed." }))
        .route_layer(middleware::from_fn_with_state(opts, l402_middleware));

    let listener = tokio::net::TcpListener::bind("0.0.0.0:8080").await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

Test it live

# Step 1 — triggers 402 + returns invoice
curl http://localhost:3000/premium
# ← { "error": "Payment Required", "invoice": "lnbc1u...", "macaroon": "eyJ..." }

# Step 2 — pay the invoice with any Lightning wallet, then:
curl http://localhost:3000/premium \
  -H "Authorization: L402 <macaroon>:<preimage>"
# ← { "data": "Payment confirmed." }

▶ Try the interactive demo

Why not Stripe?

Providers

import { BlinkProvider, OpenNodeProvider, LNbitsProvider } from "l402-kit";

// Blink (recommended — free, instant setup)
const provider = new BlinkProvider(process.env.BLINK_API_KEY!, process.env.BLINK_WALLET_ID!);

// OpenNode (production, custodial)
const provider = new OpenNodeProvider(process.env.OPENNODE_KEY!);

// LNbits (self-hosted)
const provider = new LNbitsProvider(process.env.LNBITS_KEY!, "https://your.lnbits.host");

Bring your own node — implement the LightningProvider interface in 5 lines:

import type { LightningProvider } from "l402-kit";

class MyNode implements LightningProvider {
  async createInvoice(amountSats: number) { /* return Invoice */ }
  async checkPayment(paymentHash: string) { /* return boolean */ }
}

Security model

Invoice creation:  paymentHash = SHA256(preimage)
Client payment:    Lightning Network releases preimage to payer
API verification:  SHA256(preimage) == paymentHash  ✓
Replay protection: each preimage is marked used — works exactly once
Token expiry:      macaroons expire after 1 hour

• Unforgeable — SHA256 is a one-way function; you cannot fake a preimage
• No chargebacks — cryptographic settlement, not reversible card auth
• Replay-safe — MemoryReplayAdapter (dev) or RedisReplayAdapter (production, multi-instance)
• 600+ automated tests across 5 runtimes (TS, Python, Go, Rust, Cloudflare Workers) — production-grade reliability for autonomous agent workflows
• Fully auditable — MIT, every line open source

VS Code Extension

Monitor every sat in real-time without leaving your editor.

• ⚡ Live payment feed per endpoint
• 📊 Bar chart — 1D / 7D (free) · 30D / 1Y / ALL (Pro)
• 🌍 11 languages built-in
• 🎨 Light / dark / auto theme
• 🔧 Zero config — just set your Lightning Address

Get a Lightning Address (free)

Sign up at dashboard.blink.sv — free, no credit card, instant. Your address: [email protected]

Other wallets: Wallet of Satoshi · Phoenix · Zeus · Alby

Links

MIT — use freely, build freely.

Bitcoin has no borders.

Built with ⚡ by ShinyDapps

Docs · Demo · VS Code · npm