# l402-kit

> Middleware to monetize any API with Bitcoin Lightning in 3 lines. TypeScript, Python, Go, Rust.

## What it does

l402-kit implements the L402 protocol (HTTP 402 + BOLT11 invoice + macaroon). When a client calls a protected endpoint, the server returns HTTP 402 with a Lightning invoice. The client pays the invoice (sub-second via Lightning Network) and retries with cryptographic proof of payment. No API keys, no OAuth, no chargebacks.

## Core flow

1. Client calls `GET /api/data`
2. Server returns `HTTP 402` + BOLT11 invoice + macaroon
3. Client pays invoice via Lightning (~500ms)
4. Client retries with `Authorization: L402 <macaroon>:<preimage>`
5. Middleware validates: `SHA256(preimage) == paymentHash` — pure crypto, no DB

## Install

- TypeScript/JS: `npm install l402-kit`
- Python: `pip install l402kit`
- Rust: `cargo add l402kit`
- Go: `go get github.com/shinydapps/l402-kit/go@v1.8.2`

## Minimal usage (TypeScript)

```typescript
import { l402, ManagedProvider } from "l402-kit";
const lightning = ManagedProvider.fromAddress("you@blink.sv");
app.use("/api/data", l402({ priceSats: 10, lightning }));
```

## Agent features

- MCP server: `npx l402-kit-mcp` — lets Claude/Cursor call L402-protected APIs from the IDE
- LangChain tool: auto-pay middleware inside agent chains
- Budget controls: cap agent spend at N sats/session or N sats/day
- Token delegation: orchestrator mints caveated tokens for sub-agents with lower spending limits

## Pricing

- Managed mode: 0.3% fee, zero infrastructure (uses your Lightning address)
- Sovereign mode: 0% fee, bring your own Lightning node

## Live demo

`GET https://l402kit.com/api/demo/btc-price` — returns HTTP 402 with a 1-sat invoice

## Links

- Docs: https://docs.l402kit.com
- GitHub: https://github.com/ShinyDapps/l402-kit
- npm: https://npmjs.com/package/l402-kit
- PyPI: https://pypi.org/project/l402kit
- MCP: https://glama.ai/mcp/servers/@ShinyDapps/l402-kit