Cypress
Cypress is a JavaScript-based end-to-end testing framework that runs directly inside the browser alongside the application under test, giving it fast, reliable access to the DOM and network traffic. It's known for its time-travel debugging, automatic waiting, and tight developer feedback loop.
Unlike Selenium and Playwright, which drive the browser externally through a driver protocol, Cypress runs in the same run-loop as the application — a fundamentally different architecture that gives it very fast, very reliable access to what's happening in the app, but historically limited it to Chromium-family browsers and same-origin scenarios (both have since expanded, but the underlying architecture still shapes its capabilities).
Its developer experience is a major differentiator: the Cypress Test Runner shows a live, interactive view of the app as tests execute, with the ability to "time travel" back through each step to see exactly what the DOM looked like at that point — a debugging experience many teams find faster than reading logs after the fact.
