PayMe - Paid Contact Form

PayMe is a Cloudflare Worker application that allows anyone to send you a message in exchange for a small Bitcoin Lightning Network payment. It uses Nostr Wallet Connect (NWC) to generate invoices and verify payments. Messages are embedded directly in the Lightning invoice description, so you receive them in your wallet's transaction history.

Features

• Paid Messaging: Users must pay a small fee (in sats) to send a message.
• Lightning Network: Instant payments via Bitcoin Lightning Network using NWC.
• Message Delivery: Messages appear directly in your wallet's transaction history via invoice descriptions.
• Spam Protection: Cloudflare Turnstile integration to prevent bot submissions.
• Serverless: Runs entirely on Cloudflare Workers - no database required.

Architecture

The application consists of a frontend (served by the Worker) and a backend API.

sequenceDiagram
    participant User
    participant Frontend
    participant Worker
    participant NWC as NWC Provider

    User->>Frontend: Fills Contact Form
    Frontend->>Worker: POST /api/invoice
    Worker->>Worker: Verify Turnstile Token
    Worker->>NWC: Request Invoice with Message in Description
    NWC-->>Worker: Return Invoice & Payment Hash
    Worker-->>Frontend: Return Invoice
    Frontend-->>User: Display QR Code
    
    loop Poll Payment Status
        Frontend->>Worker: GET /api/check/:hash
        Worker->>NWC: Check Invoice Status (lookup_invoice)
        alt If Paid
            Worker-->>Frontend: Paid: true
        else Not Paid
            Worker-->>Frontend: Paid: false
        end
    end

    Frontend-->>User: Show Success Message
    
    Note over User,NWC: Message appears in wallet transaction history

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User Flow

graph TD
    A[Start] --> B{Fill Form}
    B --> C[Solve Captcha]
    C --> D[Click Pay & Send]
    D --> E[Get Invoice QR]
    E --> F{Pay Invoice}
    F -->|Paid| G[Success Message]
    F -->|Timeout| H[Expired Message]

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Prerequisites

• Cloudflare Account: You need a Cloudflare account to deploy the Worker.
• Node.js & npm: For local development and deployment (Node.js v20+ required).
• Nostr Wallet Connect (NWC) URI: A connection string from your Lightning wallet (e.g., Alby, Mutiny) that allows make_invoice and lookup_invoice.
• Cloudflare Turnstile: Site Key and Secret Key for bot protection.

Setup and Configuration

1. Clone the repository

   git clone <repository-url>
   cd payme

2. Install dependencies

   npm install

3. Configure Wrangler

   • Update wrangler.toml with your specific details.
   • Important: Update the pattern in [[routes]] to match your desired domain (e.g., contact.yourdomain.com) or remove the [[routes]] block to use the default *.workers.dev domain.

4. Set Secrets You need to set the following secrets in your Cloudflare Worker:

   # The NWC connection string
   npx wrangler secret put NWC_URI
   
   # Cloudflare Turnstile Secret Key
   npx wrangler secret put TURNSTILE_SECRET_KEY
   
   # Cloudflare Turnstile Site Key (can also be in vars if public)
   npx wrangler secret put TURNSTILE_SITE_KEY

5. Environment Variables You can set non-secret variables in wrangler.toml:

   • PRICE_SATS: The cost to send a message (default: 1000 sats).

Deployment

Deploy to Cloudflare:

npm run deploy

Local Development

To run the worker locally:

npm run dev

Note: You will need to have the secrets set locally or in a .dev.vars file for local development to work fully.

License

MIT