neynar-webhook

Neynar Webhook Handler with TrueCast Integration

This is a serverless function that handles Neynar webhook events and automatically calls a protected TrueCast API using CDP wallet payments, deployed on Vercel.

Features

• Receives Neynar webhook events for cast.created
• Automatically creates CDP smart account for payments
• Calls protected x402 TrueCast API with automatic payment handling
• Handles payment authentication using viem and x402-axios

Prerequisites

1. CDP API credentials (API Key ID, Secret, and Wallet Secret)
2. A deployed x402-next-standalone TrueCast API
3. Vercel account for deployment

Deployment Steps

1. Install dependencies:

   cd neynar-webhook
   npm install

2. Install Vercel CLI (if not already installed):

   npm i -g vercel

3. Deploy to Vercel:

   vercel

   Follow the prompts:

   • Link to existing project? → No
   • What's your project's name? → neynar-webhook-handler (or your preferred name)
   • In which directory is your code located? → ./ (current directory)

4. Set Environment Variables: See env-variables.md for required environment variables that must be set in your Vercel project settings.

5. Get your webhook URL: After deployment, Vercel will provide you with a URL like: https://your-project-name.vercel.app/api/webhook

Configure Neynar Webhook

1. Go to the Neynar Developer Dashboard
2. Navigate to the Webhooks tab
3. Create a new webhook with:
   • Target URL: https://your-project-name.vercel.app/api/webhook
   • Event Type: cast.created
   • Filters:
     • mentioned_fids: Add your bot's FID (to get notified when tagged)
     • parent_author_fids: Add your bot's FID (to get notified when someone replies)

Testing

You can test locally by running:

vercel dev

This will start a local development server at http://localhost:3000

Monitoring

• View logs in the Vercel dashboard
• Check the Functions tab to see invocations and errors
• Use console.log statements in your webhook handler to debug

How It Works

1. Webhook Receipt: Receives cast.created events from Neynar
2. CDP Wallet Creation: Automatically creates or retrieves a CDP smart account
3. Payment Processing: Uses x402-axios to handle payment authentication
4. API Call: Calls the protected TrueCast API with the cast data
5. Response Handling: Logs the response and returns success/error status

Customization

The webhook automatically processes all cast.created events. You can modify api/webhook.js to:

• Add filtering logic for specific mentions or keywords
• Process additional webhook event types
• Add custom response handling
• Integrate with other services after successful API calls

Important Notes

• The function always returns a 200 status to prevent webhook retries
• As recommended by Neynar docs, avoid using ngrok or similar tunneling services
• Use your own domain or Vercel's provided URLs for reliable webhook delivery