End-to-End Testing: The Complete Developer Guide (Tools, Integration Testing, and Modern CI/CD Strategy)

Modern applications are no longer simple monoliths. Today’s systems are:* Microservices-based API-first Event-driven Cloud-native Integrated with multiple third-party servicesIn this ecosystem, validating isolated components is not enough. You must verify that the entire application workflow works correctly from start to finish.That’s where End-to-End (E2E) Testing becomes essential.This in-depth guide is written specifically for the developer community and covers:* What End-to-End testing really means How it differs from integration testing E2E testing in microservices architecture Backend vs UI E2E strategies Tools for E2E and integration testing Companies providing testing platforms CI/CD best practices Real-world examples How Keploy fits into modern backend testing What is End-to-End Testing? End-to-End testing validates the complete application workflow in a production-like environment.It simulates real user scenarios and ensures that:* Frontend interacts correctly with backend AP