Webhook Security in the Real World` Webhooks are a simple yet powerful way for services to notify each other that something interesting has happened, becoming the standard for communicating events across different SaaS services, systems, and apps. However, without good security controls, third parties could exploit webhooks for malicious activities such as sending fake events, obtaining confidential information, corrupting data, or spamming users. While many webhook providers deliver capabilities to verify the sender, validate the data sent, and mitigate attacks, there are still common patterns and challenges in implementing webhook validation. The most popular authentication method is Hash-based Message Authentication Code (HMAC), used by over two-thirds of webhooks, but implementations often lack additional controls such as timestamp verification, versioning, and zero downtime rotation. Asymmetric key encryption, OAuth 2.0, JSON Web Tokens, and JSON Web Keys are also used for security, but with varying degrees of complexity and implementation challenges. To improve webhook security, providers should provide complete documentation, use asymmetric keys, implement key rotation, and ensure secure communication protocols such as HTTPS. Listeners should review webhook documentation, restrict access based on IP, store secrets securely, rotate secrets regularly, and use strong signature algorithms.