What does e2e mean in software testing?

In software testing, e2e means end-to-end. It refers to testing an application from the start of a user workflow to the final outcome, just like a real user would experience it.

Instead of checking individual functions or services, e2e testing validates how all parts of a system work together. This includes frontend actions, backend logic, APIs, databases, and external integrations. The goal is to confirm that complete user journeys behave as expected under real conditions.

In practice, understanding the e2e meaning helps teams identify why some issues only appear in production, even when unit and integration tests pass.