Playwright and Cypress are the two leading modern web automation frameworks. In 2026, SDET interviewers focus heavily on execution architecture, browser context isolation, auto-waiting mechanisms, and network interception capabilities.

1. Browser Architecture: WebSocket Protocol vs In-Browser iFrame

Playwright communicates directly with Chromium, Firefox, and WebKit through the Chrome DevTools Protocol (CDP) and browser WebSocket connections, allowing out-of-process control and native multi-tab support.

// Playwright Multi-Context Test Case
import { test, expect } from '@playwright/test';

test('verify isolated user sessions', async ({ browser }) => {
  const adminContext = await browser.newContext();
  const userContext = await browser.newContext();

  const adminPage = await adminContext.newPage();
  const userPage = await userContext.newPage();

  await adminPage.goto('http://app.internal/admin');
  await userPage.goto('http://app.internal/user');

  await expect(adminPage.locator('#admin-panel')).toBeVisible();
  await expect(userPage.locator('#admin-panel')).not.toBeVisible();
});