How to Secure Webhooks: HMAC Verification and Best Practices

How to Secure Webhooks: HMAC Verification and Best Practices Every major webhook provider -- Stripe, GitHub, Shopify, Twilio, Discord -- sends a signature with each webhook delivery. Most developers skip verifying it during development and never add it in production. That is a serious security mistake. Without signature verification, anyone who discovers your webhook endpoint URL can send fake events to your server: forged payment confirmations, fabricated order updates, spoofed user signups. This guide explains how webhook signatures work and how to implement proper verification in your handler. Why Webhook Signature Verification Matters Your webhook endpoint is a public URL. If it accepts unauthenticated POST requests, an attacker can: Send a fake payment_intent.succeeded event to trigger order fulfillment without paying Inject malicious payloads that exploit your parsing logic Flood your endpoint with events to exhaust rate limits or cause downstream issues Signature verification so