E2E

e2e is an abbreviation commonly used in information technology to mean end-to-end. It appears in several related but distinct concepts centered on the integrity or completeness of a process from one endpoint to another.

End-to-end encryption (E2EE, e2e) is a cryptographic scheme in which data is encrypted on the sender’s device and decrypted only on the recipient's device, preventing intermediaries from reading plaintext. Keys are managed at the endpoints, and the service provider usually cannot access the content. E2EE protects confidentiality but may not hide metadata or traffic patterns; effectiveness depends on implementation, key management, and device security. It is widely used in messaging, file sharing, and collaborative tools.

End-to-end testing (E2E testing) verifies an application's full workflow from the user's perspective, including frontend interfaces, backend services, and external integrations. It aims to validate real-world behavior and user scenarios. E2E tests complement unit and integration tests and are often automated with tools such as Cypress, Selenium, or Playwright.

The end-to-end principle is a design doctrine in computer networking stating that certain functions should be implemented at endpoints rather than in the network core. It emphasizes network simplicity and relies on endpoints to provide necessary guarantees, with tradeoffs in performance and complexity.