Why Testing in Private Mode Matters?

Imagine a tester opening a new incognito window to verify a cache issue in a clean environment, then closing the bug after confirming the fix. While this appears just a routine, the real challenge begins after this. Behind this simple and familiar operation lies a deeper layer that many testers overlook — incorporating Private Mode Testing as a standard QA practice rather than limiting it to a few routine checks.

Despite its importance, Private Mode Testing is often skipped in QA workflows due to various challenges and misconceptions.

From Ignorance to Understanding

Originally built to safeguard user privacy, Private Mode empowers users to control what information is retained — including session data, browsing history, cookies, and site storage. While protecting users, it also encourages careful and thoughtful handling of application data by enforcing stricter data and storage policies. These policies can subtly, yet significantly, impact application behavior, making it crucial to validate every critical user flow in this mode.

Web applications may show no visible issues in regular mode, yet under these privacy constraints, users can encounter issues such as missing session data, blocked third-party scripts, or inconsistent interactions.

Essential Checkpoints for Private Mode Testing

Testing in private mode requires verifying how key functionalities behave under privacy-driven constraints. The following checkpoints highlight areas most impacted by these restrictions.

Feature/Area	Potential Impact in Private mode	QA Focus Areas
Cookies and Storage	Persistent storage features (user preferences, sessions, temporary data, etc.) may not work	Verify session handling/preferences work correctly during and after private browsing.  Ensure data is cleared after closing the private window  Test flows dependent on storage (e.g., login, preferences)
Logins and Authentication	Users will need to log in manually each time  Login flows relying on saved credentials may fail or behave unexpectedly	Test login flows without saved credentials and verify multi-factor authentication works as expected.
Caching	Applications relying on cached resources may experience slower load times, fail to load certain assets properly	Verify that all resources load correctly without cache.
Extensions and Plugins	Features depending on extensions or plugins may not work as expected or could fail entirely	Test application’s functionality without extensions.
Permissions (like location, camera, or notifications)	Features relying on permissions may not work if prompts are blocked or denied, affecting user experience	Verify that permission prompts appear as expected  The app handles denied or missing permissions gracefully
Form Autofill and Saved Data	Users need to manually fill in all fields.   Form design or validation relying on auto-filled values may cause errors or a poor user experience	Manually complete forms to verify field validations, error handling, and overall user experience without auto-filled data
Analytics and Tracking	Key metrics may be underreported or missing, affecting data accuracy and insights drawn from user behavior.	Verify behavior of analytics tools.   Ensure critical events are tracked properly. Validate fallback logic if tracking fails.

Final Thoughts

Private mode testing challenges traditional QA assumptions by requiring teams to validate application behavior in constrained environments. Embracing this shift not only improves test coverage but also exposes issues that may remain hidden in standard browsing conditions.

References

• How Chrome Incognito keeps your browsing private - Google Chrome Help  

• Incognito Mode: Is Private Browsing Really Private?  

• Why Use An Incognito Window When Testing AccessAlly | KB AccessAlly  

• Incognito Mode  

• Private and Incognito Browsing - Dr. Mike Murphy