42Crunch API Protection provides runtime security for APIs through a micro-firewall approach that enforces security policies based on OpenAPI contracts. The platform combines shift-left security testing during design and development with shield-right runtime protection throughout the API lifecycle. The solution automatically enforces content validation by deploying directly from CI/CD pipelines and reconfigures when OpenAPI contracts change. It uses a positive security model based on data conformance to OpenAPI specifications to distinguish legitimate API traffic from malicious attacks. The platform detects OWASP API Security Top 10 issues including data leakage, overflows, mass assignment, broken authentication, and security misconfigurations. It identifies vulnerabilities triggered by wrong HTTP verbs, incorrect paths, wrong content types, improper data formats, violations of API constraints, and data injection attempts. Traffic throttling capabilities actively prevent Denial of Service and brute-force attacks based on configurable criteria. In microservice deployments, API Protection is deployed separately with each microservice instance, enabling per-instance rate limiting enforcement. The solution integrates with IDE, CI/CD pipelines, API gateways, runtime containers, and SIEM systems to provide comprehensive API security coverage from design through runtime.