The Vercel Web Application Firewall (WAF) is a new security feature that adds an extra layer of defense against various web threats directly within the Vercel platform. It provides first-party security at the edge, reducing latency and ensuring only legitimate users access applications hosted on Vercel. The WAF offers customizable rules engine, framework-aware rules, managed rulesets, observability, rate limiting (beta), instant propagation, and instant rollback features for comprehensive protection. This new feature is part of Vercel's commitment to building a web that is secure by default, leveraging its unique framework-defined infrastructure (FdI) and inherent understanding of applications.