Troubleshooting web applications from the browser
Work out whether a web app problem lives in the service, the browser, the device or the network: isolate with cheap tests (a colleague, a private window, another browser), deal with cache, cookies, extensions and privacy protections precisely, use the browser's developer tools to find the failing request, and never ask users to paste code or click through security warnings.
- Level
- Intermediate
- Length
- About 50 minutes
- Contents
- 3 lessons · 1 video · final exam
- Status
- Published · updated 1 Oct 2026
Skills you'll practise
- Order isolation tests from least to most disruptive and interpret their results
- Explain the difference between cache, cookies and site data, and clear one site's data instead of everything
- Recognize when extensions, pop-up blockers, third-party cookie restrictions or locale settings cause a symptom
- Use the Console and Network panels to identify a failing request and its timing without changing anything
- Respond safely to requests to paste code into the console and to certificate or mixed-content warnings
Course outline
- 1.Troubleshooting web apps from the browserVideo · 3 min
- 2.Isolate: service, browser, device or networkLesson · 16 min
- 3.Cache, cookies, extensions and settingsLesson · 17 min
- 4.Developer tools for support: look, don't pasteLesson · 17 min
- 5.Troubleshooting web applications from the browser: knowledge checkKnowledge check · 20 questions
- 6.Final exam9 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Chrome for Developers: Network features reference (Preserve log, Disable cache, HAR export)
- Chrome for Developers: Console overview
- Chrome for Developers: Self-XSS protection in DevTools (pasting into the Console is blocked until 'allow pasting' is typed)
- Google Chrome Help: How Incognito mode protects your privacy
- Chrome Web Store Help: Install and manage extensions (Allow in Incognito, site access)
- MDN Web Docs: Mixed content
- MDN Web Docs: Third-party cookies
- General technical-support practice
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