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Specialized Testing

What Is Cross-Browser Testing?

Cross-browser testing is the practice of verifying that a web application works correctly and looks consistent across different browsers (Chrome, Firefox, Safari, Edge), browser versions, and operating systems.

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In Depth

Different browsers use different rendering engines: Chromium powers Chrome and Edge, Gecko powers Firefox, and WebKit powers Safari. These engines interpret CSS, JavaScript, and HTML slightly differently, which can cause visual differences, layout breaks, and functionality bugs.

Cross-browser testing strategies range from manual spot-checking (quick but unreliable) to fully automated multi-browser test suites. The pragmatic approach is to automate critical flows across your most important browsers and visually spot-check the rest.

Playwright excels at cross-browser testing because it supports Chromium, Firefox, and WebKit natively. Selenium supports all browsers through WebDriver. Cloud platforms like BrowserStack and Sauce Labs provide access to hundreds of browser and OS combinations.

Key decisions: which browsers to test (based on your analytics data), how many browser versions to support, whether to test on real devices or emulators for mobile browsers, and how to handle visual differences (pixel-perfect vs. functionally equivalent).

Why Interviewers Ask About This

Cross-browser testing is a fundamental QA skill. Interviewers expect you to have a strategy for ensuring browser compatibility, especially for customer-facing applications.

Example Scenario

A Playwright test suite runs all E2E tests against Chromium, with a weekly scheduled run against Firefox and WebKit. The WebKit run catches a Safari-specific bug where a CSS flexbox layout breaks the checkout form on iOS devices. The bug is fixed before any customer reports it.

Interview Tip

Discuss your strategy: which browsers do you prioritize and why (based on analytics). Mention tools you use and how you balance thoroughness with pipeline speed. Explain the difference between visual testing and functional testing across browsers.

Related Terms

Explore related glossary terms to deepen your understanding.

End-to-End TestingEnd-to-end (E2E) testing validates complete user workflows from start to finish, simulating real user behavior across the entire application stack — frontend, backend, database, and external integrations.
Visual Regression TestingVisual regression testing is the practice of capturing screenshots or visual snapshots of UI components or pages and comparing them against approved baselines to detect unintended visual changes.
PlaywrightPlaywright is an open-source browser automation framework developed by Microsoft that enables reliable end-to-end testing across Chromium, Firefox, and WebKit with a single API.
SeleniumSelenium is an open-source browser automation framework that uses the WebDriver protocol to control browsers programmatically, enabling automated testing of web applications across multiple browsers and programming languages.
Test AutomationTest automation is the practice of using software tools and scripts to execute tests, compare actual outcomes to expected outcomes, and report results — replacing or augmenting manual test execution.

Related Resources

Dive deeper with these related interview prep pages.

Playwright vs Selenium 2026Automation Engineer Interview Prep

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Written by Aston Cook, Senior QA EngineerLast updated: March 2026