Webhook Signature Verifier

A simple Next.js application for debugging webhook signatures. This tool verifies HMAC SHA-256 signatures on webhook payloads and displays the results.

Features

• Verify webhook signatures using HMAC SHA-256
• Display request details and validation results
• Simple web interface for testing
• API endpoint for integration with external tools

Getting Started

Prerequisites

• Node.js (version 16 or later recommended)
• npm

Installation

1. Clone the repository

   git clone https://github.com/yourusername/webhook-signature-verifier.git
   cd webhook-signature-verifier

2. Install dependencies

   npm install

3. Start the development server

   npm run dev

4. Open http://localhost:3000 in your browser

Usage

Web Interface

The web interface allows you to:

• Enter a JSON payload
• Send a test webhook to the API endpoint
• View the response and validation results

API Endpoint

You can send webhooks directly to the API endpoint:

curl -X POST \
  http://localhost:3000/api/webhook \
  -H 'Content-Type: application/json' \
  -H 'X-Signature: [your-signature-here]' \
  -d '{"event":"test","data":{"id":123}}'

Creating a Valid Signature

To create a valid signature, compute an HMAC with SHA-256 using the shared secret:

const crypto = require('crypto');
const payload = JSON.stringify({event: "test", data: {id: 123}});
const hmac = crypto.createHmac('sha256', 'sharedSecretHere');
hmac.update(payload);
const signature = hmac.digest('hex');
console.log(signature);

Configuration

You can modify the configuration in lib/constants.js:

• SHARED_SECRET: The secret key used for HMAC calculation
• SIGNATURE_HEADER_NAME: The header name used for the signature

Testing

npm test