Unit tests prove that the components work. E2E tests prove that the Application works. Playwright is the leading tool for simulating a real user's journey through your site in actual browsers.
Unlike older tools (Cypress), Playwright is Multi-tab, Multi-browser, and Multi-context. It can simulate a user logged in as an Admin in Chrome and a standard user in Firefox simultaneously. It is incredibly fast and has built-in auto-waiting logic to prevent 'Flaky' tests.
Don't test every tiny UI state in E2E. Focus on the money flows: Login -> Add to Cart -> Checkout -> Payment Success. If these work, your business is running.
Q: "What is the biggest challenge of E2E testing and how do you solve it?"
Architect Answer: "**Flakiness**. Tests failing because an API was slow or a loader took 10ms too long. Playwright solves this with 'Auto-waiting'—it won't click a button until it is visible, enabled, and stopped moving. We also use 'Traces' that record a video and a full console/network log of every test run, allowing us to debug failures in CI/CD within seconds."