Build an L402 API Paywall with Cloudflare Workers

HTTP has a status code for payments: 402 Payment Required. It sat unused for decades. L402 gives it a purpose.

When a client hits your API without paying, you return a 402 with a Lightning invoice. The client pays, retries with proof, and gets the response. No API keys. No subscriptions. No billing dashboards.

The Stack

• Cloudflare Workers — serverless runtime, free tier
• LNbits — Lightning wallet with REST API (runs on Alby Hub, your own node, or lnbits.com)

The Flow

1. Client POSTs to your API
2. Worker creates a Lightning invoice via LNbits
3. Returns HTTP 402 with the invoice
4. Client pays the invoice
5. Client retries with the payment_hash
6. Worker verifies payment via LNbits
7. Returns the data

Full tutorial with working code: https://maximumsats.com/blog/l402-api-paywall-cloudflare-workers

Covers setup, deployment, the WWW-Authenticate header for automated clients, free tier implementation, and CORS.

The entire deployment costs $0. Revenue is 100% margin. This is how APIs should work in a world with programmable money.